CVE-2026-1965 (GCVE-0-2026-1965)

Vulnerability from cvelistv5 – Published: 2026-03-11 10:08 – Updated: 2026-09-15 06:02
VLAI
Title
bad reuse of HTTP Negotiate connection
Summary
libcurl can in some circumstances reuse the wrong connection when asked to do an Negotiate-authenticated HTTP or HTTPS request. libcurl features a pool of recent connections so that subsequent requests can reuse an existing connection to avoid overhead. When reusing a connection a range of criterion must first be met. Due to a logical error in the code, a request that was issued by an application could wrongfully reuse an existing connection to the same server that was authenticated using different credentials. One underlying reason being that Negotiate sometimes authenticates *connections* and not *requests*, contrary to how HTTP is designed to work. An application that allows Negotiate authentication to a server (that responds wanting Negotiate) with `user1:password1` and then does another operation to the same server also using Negotiate but with `user2:password2` (while the previous connection is still alive) - the second request wrongly reused the same connection and since it then sees that the Negotiate negotiation is already made, it sends the request over that connection thinking it uses the user2 credentials when it is in fact still using the connection authenticated for user1... The set of authentication methods to use is set with `CURLOPT_HTTPAUTH`. Applications can disable libcurl's reuse of connections and thus mitigate this problem, by using one of the following libcurl options to alter how connections are or are not reused: `CURLOPT_FRESH_CONNECT`, `CURLOPT_MAXCONNECTS` and `CURLMOPT_MAX_HOST_CONNECTIONS` (if using the curl_multi API).
SSVC
Exploitation: none Automatable: no Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-03-11 14:31 UTC
CWE
  • CWE-305 - Authentication Bypass by Primary Weakness
Impacted products
Vendor Product Version
curl curl Affected: 7.10.6 , < 8.14.2 (semver)
Affected: 8.15.0 , < 8.16.1 (semver)
Affected: 8.17.0 , < 8.19.0 (semver)
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curl curl Affected: e56ae1426cb7a0a4a427cf8d6099a821fdaae428 , < f1a39f221d57354990e3eeeddc3404aede2aff70 (git)
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curl curl Affected: 8.18.0
Affected: 8.17.0
Affected: 8.16.0
Affected: 8.15.0
Affected: 8.14.1
Affected: 8.14.0
Affected: 8.13.0
Affected: 8.12.1
Affected: 8.12.0
Affected: 8.11.1
Affected: 8.11.0
Affected: 8.10.1
Affected: 8.10.0
Affected: 8.9.1
Affected: 8.9.0
Affected: 8.8.0
Affected: 8.7.1
Affected: 8.7.0
Affected: 8.6.0
Affected: 8.5.0
Affected: 8.4.0
Affected: 8.3.0
Affected: 8.2.1
Affected: 8.2.0
Affected: 8.1.2
Affected: 8.1.1
Affected: 8.1.0
Affected: 8.0.1
Affected: 8.0.0
Affected: 7.88.1
Affected: 7.88.0
Affected: 7.87.0
Affected: 7.86.0
Affected: 7.85.0
Affected: 7.84.0
Affected: 7.83.1
Affected: 7.83.0
Affected: 7.82.0
Affected: 7.81.0
Affected: 7.80.0
Affected: 7.79.1
Affected: 7.79.0
Affected: 7.78.0
Affected: 7.77.0
Affected: 7.76.1
Affected: 7.76.0
Affected: 7.75.0
Affected: 7.74.0
Affected: 7.73.0
Affected: 7.72.0
Affected: 7.71.1
Affected: 7.71.0
Affected: 7.70.0
Affected: 7.69.1
Affected: 7.69.0
Affected: 7.68.0
Affected: 7.67.0
Affected: 7.66.0
Affected: 7.65.3
Affected: 7.65.2
Affected: 7.65.1
Affected: 7.65.0
Affected: 7.64.1
Affected: 7.64.0
Affected: 7.63.0
Affected: 7.62.0
Affected: 7.61.1
Affected: 7.61.0
Affected: 7.60.0
Affected: 7.59.0
Affected: 7.58.0
Affected: 7.57.0
Affected: 7.56.1
Affected: 7.56.0
Affected: 7.55.1
Affected: 7.55.0
Affected: 7.54.1
Affected: 7.54.0
Affected: 7.53.1
Affected: 7.53.0
Affected: 7.52.1
Affected: 7.52.0
Affected: 7.51.0
Affected: 7.50.3
Affected: 7.50.2
Affected: 7.50.1
Affected: 7.50.0
Affected: 7.49.1
Affected: 7.49.0
Affected: 7.48.0
Affected: 7.47.1
Affected: 7.47.0
Affected: 7.46.0
Affected: 7.45.0
Affected: 7.44.0
Affected: 7.43.0
Affected: 7.42.1
Affected: 7.42.0
Affected: 7.41.0
Affected: 7.40.0
Affected: 7.39.0
Affected: 7.38.0
Affected: 7.37.1
Affected: 7.37.0
Affected: 7.36.0
Affected: 7.35.0
Affected: 7.34.0
Affected: 7.33.0
Affected: 7.32.0
Affected: 7.31.0
Affected: 7.30.0
Affected: 7.29.0
Affected: 7.28.1
Affected: 7.28.0
Affected: 7.27.0
Affected: 7.26.0
Affected: 7.25.0
Affected: 7.24.0
Affected: 7.23.1
Affected: 7.23.0
Affected: 7.22.0
Affected: 7.21.7
Affected: 7.21.6
Affected: 7.21.5
Affected: 7.21.4
Affected: 7.21.3
Affected: 7.21.2
Affected: 7.21.1
Affected: 7.21.0
Affected: 7.20.1
Affected: 7.20.0
Affected: 7.19.7
Affected: 7.19.6
Affected: 7.19.5
Affected: 7.19.4
Affected: 7.19.3
Affected: 7.19.2
Affected: 7.19.1
Affected: 7.19.0
Affected: 7.18.2
Affected: 7.18.1
Affected: 7.18.0
Affected: 7.17.1
Affected: 7.17.0
Affected: 7.16.4
Affected: 7.16.3
Affected: 7.16.2
Affected: 7.16.1
Affected: 7.16.0
Affected: 7.15.5
Affected: 7.15.4
Affected: 7.15.3
Affected: 7.15.2
Affected: 7.15.1
Affected: 7.15.0
Affected: 7.14.1
Affected: 7.14.0
Affected: 7.13.2
Affected: 7.13.1
Affected: 7.13.0
Affected: 7.12.3
Affected: 7.12.2
Affected: 7.12.1
Affected: 7.12.0
Affected: 7.11.2
Affected: 7.11.1
Affected: 7.11.0
Affected: 7.10.8
Affected: 7.10.7
Affected: 7.10.6
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Show details on NVD website

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              "version": "8.0.1"
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              "status": "affected",
              "version": "8.0.0"
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            {
              "status": "affected",
              "version": "7.85.0"
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            {
              "status": "affected",
              "version": "7.84.0"
            },
            {
              "status": "affected",
              "version": "7.83.1"
            },
            {
              "status": "affected",
              "version": "7.83.0"
            },
            {
              "status": "affected",
              "version": "7.82.0"
            },
            {
              "status": "affected",
              "version": "7.81.0"
            },
            {
              "status": "affected",
              "version": "7.80.0"
            },
            {
              "status": "affected",
              "version": "7.79.1"
            },
            {
              "status": "affected",
              "version": "7.79.0"
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            {
              "status": "affected",
              "version": "7.78.0"
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            {
              "status": "affected",
              "version": "7.77.0"
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            {
              "status": "affected",
              "version": "7.76.1"
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            {
              "status": "affected",
              "version": "7.76.0"
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            {
              "status": "affected",
              "version": "7.75.0"
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              "version": "7.74.0"
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              "version": "7.73.0"
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              "status": "affected",
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              "status": "affected",
              "version": "7.71.1"
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              "status": "affected",
              "version": "7.71.0"
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              "status": "affected",
              "version": "7.70.0"
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              "status": "affected",
              "version": "7.69.1"
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              "status": "affected",
              "version": "7.69.0"
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            {
              "status": "affected",
              "version": "7.68.0"
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              "status": "affected",
              "version": "7.67.0"
            },
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              "status": "affected",
              "version": "7.66.0"
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              "status": "affected",
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              "status": "affected",
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              "status": "affected",
              "version": "7.65.1"
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              "status": "affected",
              "version": "7.65.0"
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              "status": "affected",
              "version": "7.64.1"
            },
            {
              "status": "affected",
              "version": "7.64.0"
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            {
              "status": "affected",
              "version": "7.63.0"
            },
            {
              "status": "affected",
              "version": "7.62.0"
            },
            {
              "status": "affected",
              "version": "7.61.1"
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            {
              "status": "affected",
              "version": "7.61.0"
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            {
              "status": "affected",
              "version": "7.60.0"
            },
            {
              "status": "affected",
              "version": "7.59.0"
            },
            {
              "status": "affected",
              "version": "7.58.0"
            },
            {
              "status": "affected",
              "version": "7.57.0"
            },
            {
              "status": "affected",
              "version": "7.56.1"
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            {
              "status": "affected",
              "version": "7.56.0"
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            {
              "status": "affected",
              "version": "7.55.1"
            },
            {
              "status": "affected",
              "version": "7.55.0"
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            {
              "status": "affected",
              "version": "7.54.1"
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            {
              "status": "affected",
              "version": "7.54.0"
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            {
              "status": "affected",
              "version": "7.53.1"
            },
            {
              "status": "affected",
              "version": "7.53.0"
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            {
              "status": "affected",
              "version": "7.52.1"
            },
            {
              "status": "affected",
              "version": "7.52.0"
            },
            {
              "status": "affected",
              "version": "7.51.0"
            },
            {
              "status": "affected",
              "version": "7.50.3"
            },
            {
              "status": "affected",
              "version": "7.50.2"
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            {
              "status": "affected",
              "version": "7.50.1"
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            {
              "status": "affected",
              "version": "7.50.0"
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            {
              "status": "affected",
              "version": "7.49.1"
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            {
              "status": "affected",
              "version": "7.49.0"
            },
            {
              "status": "affected",
              "version": "7.48.0"
            },
            {
              "status": "affected",
              "version": "7.47.1"
            },
            {
              "status": "affected",
              "version": "7.47.0"
            },
            {
              "status": "affected",
              "version": "7.46.0"
            },
            {
              "status": "affected",
              "version": "7.45.0"
            },
            {
              "status": "affected",
              "version": "7.44.0"
            },
            {
              "status": "affected",
              "version": "7.43.0"
            },
            {
              "status": "affected",
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            },
            {
              "status": "affected",
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              "status": "affected",
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              "status": "affected",
              "version": "7.40.0"
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              "status": "affected",
              "version": "7.39.0"
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              "status": "affected",
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              "status": "affected",
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            {
              "status": "affected",
              "version": "7.37.0"
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            {
              "status": "affected",
              "version": "7.36.0"
            },
            {
              "status": "affected",
              "version": "7.35.0"
            },
            {
              "status": "affected",
              "version": "7.34.0"
            },
            {
              "status": "affected",
              "version": "7.33.0"
            },
            {
              "status": "affected",
              "version": "7.32.0"
            },
            {
              "status": "affected",
              "version": "7.31.0"
            },
            {
              "status": "affected",
              "version": "7.30.0"
            },
            {
              "status": "affected",
              "version": "7.29.0"
            },
            {
              "status": "affected",
              "version": "7.28.1"
            },
            {
              "status": "affected",
              "version": "7.28.0"
            },
            {
              "status": "affected",
              "version": "7.27.0"
            },
            {
              "status": "affected",
              "version": "7.26.0"
            },
            {
              "status": "affected",
              "version": "7.25.0"
            },
            {
              "status": "affected",
              "version": "7.24.0"
            },
            {
              "status": "affected",
              "version": "7.23.1"
            },
            {
              "status": "affected",
              "version": "7.23.0"
            },
            {
              "status": "affected",
              "version": "7.22.0"
            },
            {
              "status": "affected",
              "version": "7.21.7"
            },
            {
              "status": "affected",
              "version": "7.21.6"
            },
            {
              "status": "affected",
              "version": "7.21.5"
            },
            {
              "status": "affected",
              "version": "7.21.4"
            },
            {
              "status": "affected",
              "version": "7.21.3"
            },
            {
              "status": "affected",
              "version": "7.21.2"
            },
            {
              "status": "affected",
              "version": "7.21.1"
            },
            {
              "status": "affected",
              "version": "7.21.0"
            },
            {
              "status": "affected",
              "version": "7.20.1"
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            {
              "status": "affected",
              "version": "7.20.0"
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            {
              "status": "affected",
              "version": "7.19.7"
            },
            {
              "status": "affected",
              "version": "7.19.6"
            },
            {
              "status": "affected",
              "version": "7.19.5"
            },
            {
              "status": "affected",
              "version": "7.19.4"
            },
            {
              "status": "affected",
              "version": "7.19.3"
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              "status": "affected",
              "version": "7.19.2"
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              "status": "affected",
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              "status": "affected",
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              "status": "affected",
              "version": "7.16.0"
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              "status": "affected",
              "version": "7.15.5"
            },
            {
              "status": "affected",
              "version": "7.15.4"
            },
            {
              "status": "affected",
              "version": "7.15.3"
            },
            {
              "status": "affected",
              "version": "7.15.2"
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            {
              "status": "affected",
              "version": "7.15.1"
            },
            {
              "status": "affected",
              "version": "7.15.0"
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            {
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              "status": "affected",
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              "status": "affected",
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            {
              "status": "affected",
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            },
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        },
        {
          "url": "https://curl.se/docs/CVE-2026-1965.html"
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      "title": "bad reuse of HTTP Negotiate connection",
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          "package": "curl",
          "severity": "Medium",
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        "id": "CURL-CVE-2026-1965",
        "modified": "2026-09-07T10:34:51.00Z",
        "published": "2026-03-11T08:00:00.00Z",
        "schema_version": "1.5.0",
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    "state": "PUBLISHED"
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                {
                  "status": "affected",
                  "version": "7.41.0"
                },
                {
                  "status": "affected",
                  "version": "7.40.0"
                },
                {
                  "status": "affected",
                  "version": "7.39.0"
                },
                {
                  "status": "affected",
                  "version": "7.38.0"
                },
                {
                  "status": "affected",
                  "version": "7.37.1"
                },
                {
                  "status": "affected",
                  "version": "7.37.0"
                },
                {
                  "status": "affected",
                  "version": "7.36.0"
                },
                {
                  "status": "affected",
                  "version": "7.35.0"
                },
                {
                  "status": "affected",
                  "version": "7.34.0"
                },
                {
                  "status": "affected",
                  "version": "7.33.0"
                },
                {
                  "status": "affected",
                  "version": "7.32.0"
                },
                {
                  "status": "affected",
                  "version": "7.31.0"
                },
                {
                  "status": "affected",
                  "version": "7.30.0"
                },
                {
                  "status": "affected",
                  "version": "7.29.0"
                },
                {
                  "status": "affected",
                  "version": "7.28.1"
                },
                {
                  "status": "affected",
                  "version": "7.28.0"
                },
                {
                  "status": "affected",
                  "version": "7.27.0"
                },
                {
                  "status": "affected",
                  "version": "7.26.0"
                },
                {
                  "status": "affected",
                  "version": "7.25.0"
                },
                {
                  "status": "affected",
                  "version": "7.24.0"
                },
                {
                  "status": "affected",
                  "version": "7.23.1"
                },
                {
                  "status": "affected",
                  "version": "7.23.0"
                },
                {
                  "status": "affected",
                  "version": "7.22.0"
                },
                {
                  "status": "affected",
                  "version": "7.21.7"
                },
                {
                  "status": "affected",
                  "version": "7.21.6"
                },
                {
                  "status": "affected",
                  "version": "7.21.5"
                },
                {
                  "status": "affected",
                  "version": "7.21.4"
                },
                {
                  "status": "affected",
                  "version": "7.21.3"
                },
                {
                  "status": "affected",
                  "version": "7.21.2"
                },
                {
                  "status": "affected",
                  "version": "7.21.1"
                },
                {
                  "status": "affected",
                  "version": "7.21.0"
                },
                {
                  "status": "affected",
                  "version": "7.20.1"
                },
                {
                  "status": "affected",
                  "version": "7.20.0"
                },
                {
                  "status": "affected",
                  "version": "7.19.7"
                },
                {
                  "status": "affected",
                  "version": "7.19.6"
                },
                {
                  "status": "affected",
                  "version": "7.19.5"
                },
                {
                  "status": "affected",
                  "version": "7.19.4"
                },
                {
                  "status": "affected",
                  "version": "7.19.3"
                },
                {
                  "status": "affected",
                  "version": "7.19.2"
                },
                {
                  "status": "affected",
                  "version": "7.19.1"
                },
                {
                  "status": "affected",
                  "version": "7.19.0"
                },
                {
                  "status": "affected",
                  "version": "7.18.2"
                },
                {
                  "status": "affected",
                  "version": "7.18.1"
                },
                {
                  "status": "affected",
                  "version": "7.18.0"
                },
                {
                  "status": "affected",
                  "version": "7.17.1"
                },
                {
                  "status": "affected",
                  "version": "7.17.0"
                },
                {
                  "status": "affected",
                  "version": "7.16.4"
                },
                {
                  "status": "affected",
                  "version": "7.16.3"
                },
                {
                  "status": "affected",
                  "version": "7.16.2"
                },
                {
                  "status": "affected",
                  "version": "7.16.1"
                },
                {
                  "status": "affected",
                  "version": "7.16.0"
                },
                {
                  "status": "affected",
                  "version": "7.15.5"
                },
                {
                  "status": "affected",
                  "version": "7.15.4"
                },
                {
                  "status": "affected",
                  "version": "7.15.3"
                },
                {
                  "status": "affected",
                  "version": "7.15.2"
                },
                {
                  "status": "affected",
                  "version": "7.15.1"
                },
                {
                  "status": "affected",
                  "version": "7.15.0"
                },
                {
                  "status": "affected",
                  "version": "7.14.1"
                },
                {
                  "status": "affected",
                  "version": "7.14.0"
                },
                {
                  "status": "affected",
                  "version": "7.13.2"
                },
                {
                  "status": "affected",
                  "version": "7.13.1"
                },
                {
                  "status": "affected",
                  "version": "7.13.0"
                },
                {
                  "status": "affected",
                  "version": "7.12.3"
                },
                {
                  "status": "affected",
                  "version": "7.12.2"
                },
                {
                  "status": "affected",
                  "version": "7.12.1"
                },
                {
                  "status": "affected",
                  "version": "7.12.0"
                },
                {
                  "status": "affected",
                  "version": "7.11.2"
                },
                {
                  "status": "affected",
                  "version": "7.11.1"
                },
                {
                  "status": "affected",
                  "version": "7.11.0"
                },
                {
                  "status": "affected",
                  "version": "7.10.8"
                },
                {
                  "status": "affected",
                  "version": "7.10.7"
                },
                {
                  "status": "affected",
                  "version": "7.10.6"
                }
              ]
            }
          ],
          "credits": [
            {
              "lang": "en",
              "type": "finder",
              "value": "Zhicheng Chen"
            },
            {
              "lang": "en",
              "type": "remediation developer",
              "value": "Daniel Stenberg"
            }
          ],
          "descriptions": [
            {
              "lang": "en",
              "value": "libcurl can in some circumstances reuse the wrong connection when asked to do\nan Negotiate-authenticated HTTP or HTTPS request.\n\nlibcurl features a pool of recent connections so that subsequent requests can\nreuse an existing connection to avoid overhead.\n\nWhen reusing a connection a range of criterion must first be met. Due to a\nlogical error in the code, a request that was issued by an application could\nwrongfully reuse an existing connection to the same server that was\nauthenticated using different credentials. One underlying reason being that\nNegotiate sometimes authenticates *connections* and not *requests*, contrary\nto how HTTP is designed to work.\n\nAn application that allows Negotiate authentication to a server (that responds\nwanting Negotiate) with `user1:password1` and then does another operation to\nthe same server also using Negotiate but with `user2:password2` (while the\nprevious connection is still alive) - the second request wrongly reused the\nsame connection and since it then sees that the Negotiate negotiation is\nalready made, it sends the request over that connection thinking it uses\nthe user2 credentials when it is in fact still using the connection\nauthenticated for user1...\n\nThe set of authentication methods to use is set with `CURLOPT_HTTPAUTH`.\n\nApplications can disable libcurl\u0027s reuse of connections and thus mitigate this\nproblem, by using one of the following libcurl options to alter how\nconnections are or are not reused: `CURLOPT_FRESH_CONNECT`,\n`CURLOPT_MAXCONNECTS` and `CURLMOPT_MAX_HOST_CONNECTIONS` (if using the\ncurl_multi API)."
            }
          ],
          "problemTypes": [
            {
              "descriptions": [
                {
                  "cweId": "CWE-305",
                  "description": "Authentication Bypass by Primary Weakness",
                  "lang": "en",
                  "type": "CWE"
                }
              ]
            }
          ],
          "providerMetadata": {
            "dateUpdated": "2026-09-15T06:02:49.175Z",
            "orgId": "2499f714-1537-4658-8207-48ae4bb9eae9",
            "shortName": "curl"
          },
          "references": [
            {
              "url": "https://curl.se/docs/CVE-2026-1965.json"
            },
            {
              "url": "https://curl.se/docs/CVE-2026-1965.html"
            }
          ],
          "title": "bad reuse of HTTP Negotiate connection",
          "x_generator": {
            "engine": "cvelib 1.8.0"
          },
          "x_osv": {
            "affected": [
              {
                "ranges": [
                  {
                    "events": [
                      {
                        "introduced": "7.10.6"
                      },
                      {
                        "fixed": "8.14.2"
                      },
                      {
                        "introduced": "8.15.0"
                      },
                      {
                        "fixed": "8.16.1"
                      },
                      {
                        "introduced": "8.17.0"
                      },
                      {
                        "fixed": "8.19.0"
                      }
                    ],
                    "type": "SEMVER"
                  },
                  {
                    "events": [
                      {
                        "introduced": "e56ae1426cb7a0a4a427cf8d6099a821fdaae428"
                      },
                      {
                        "fixed": "f1a39f221d57354990e3eeeddc3404aede2aff70"
                      }
                    ],
                    "repo": "https://github.com/curl/curl.git",
                    "type": "GIT"
                  }
                ],
                "versions": [
                  "8.18.0",
                  "8.17.0",
                  "8.16.0",
                  "8.15.0",
                  "8.14.1",
                  "8.14.0",
                  "8.13.0",
                  "8.12.1",
                  "8.12.0",
                  "8.11.1",
                  "8.11.0",
                  "8.10.1",
                  "8.10.0",
                  "8.9.1",
                  "8.9.0",
                  "8.8.0",
                  "8.7.1",
                  "8.7.0",
                  "8.6.0",
                  "8.5.0",
                  "8.4.0",
                  "8.3.0",
                  "8.2.1",
                  "8.2.0",
                  "8.1.2",
                  "8.1.1",
                  "8.1.0",
                  "8.0.1",
                  "8.0.0",
                  "7.88.1",
                  "7.88.0",
                  "7.87.0",
                  "7.86.0",
                  "7.85.0",
                  "7.84.0",
                  "7.83.1",
                  "7.83.0",
                  "7.82.0",
                  "7.81.0",
                  "7.80.0",
                  "7.79.1",
                  "7.79.0",
                  "7.78.0",
                  "7.77.0",
                  "7.76.1",
                  "7.76.0",
                  "7.75.0",
                  "7.74.0",
                  "7.73.0",
                  "7.72.0",
                  "7.71.1",
                  "7.71.0",
                  "7.70.0",
                  "7.69.1",
                  "7.69.0",
                  "7.68.0",
                  "7.67.0",
                  "7.66.0",
                  "7.65.3",
                  "7.65.2",
                  "7.65.1",
                  "7.65.0",
                  "7.64.1",
                  "7.64.0",
                  "7.63.0",
                  "7.62.0",
                  "7.61.1",
                  "7.61.0",
                  "7.60.0",
                  "7.59.0",
                  "7.58.0",
                  "7.57.0",
                  "7.56.1",
                  "7.56.0",
                  "7.55.1",
                  "7.55.0",
                  "7.54.1",
                  "7.54.0",
                  "7.53.1",
                  "7.53.0",
                  "7.52.1",
                  "7.52.0",
                  "7.51.0",
                  "7.50.3",
                  "7.50.2",
                  "7.50.1",
                  "7.50.0",
                  "7.49.1",
                  "7.49.0",
                  "7.48.0",
                  "7.47.1",
                  "7.47.0",
                  "7.46.0",
                  "7.45.0",
                  "7.44.0",
                  "7.43.0",
                  "7.42.1",
                  "7.42.0",
                  "7.41.0",
                  "7.40.0",
                  "7.39.0",
                  "7.38.0",
                  "7.37.1",
                  "7.37.0",
                  "7.36.0",
                  "7.35.0",
                  "7.34.0",
                  "7.33.0",
                  "7.32.0",
                  "7.31.0",
                  "7.30.0",
                  "7.29.0",
                  "7.28.1",
                  "7.28.0",
                  "7.27.0",
                  "7.26.0",
                  "7.25.0",
                  "7.24.0",
                  "7.23.1",
                  "7.23.0",
                  "7.22.0",
                  "7.21.7",
                  "7.21.6",
                  "7.21.5",
                  "7.21.4",
                  "7.21.3",
                  "7.21.2",
                  "7.21.1",
                  "7.21.0",
                  "7.20.1",
                  "7.20.0",
                  "7.19.7",
                  "7.19.6",
                  "7.19.5",
                  "7.19.4",
                  "7.19.3",
                  "7.19.2",
                  "7.19.1",
                  "7.19.0",
                  "7.18.2",
                  "7.18.1",
                  "7.18.0",
                  "7.17.1",
                  "7.17.0",
                  "7.16.4",
                  "7.16.3",
                  "7.16.2",
                  "7.16.1",
                  "7.16.0",
                  "7.15.5",
                  "7.15.4",
                  "7.15.3",
                  "7.15.2",
                  "7.15.1",
                  "7.15.0",
                  "7.14.1",
                  "7.14.0",
                  "7.13.2",
                  "7.13.1",
                  "7.13.0",
                  "7.12.3",
                  "7.12.2",
                  "7.12.1",
                  "7.12.0",
                  "7.11.2",
                  "7.11.1",
                  "7.11.0",
                  "7.10.8",
                  "7.10.7",
                  "7.10.6"
                ]
              }
            ],
            "aliases": [
              "CVE-2026-1965"
            ],
            "credits": [
              {
                "name": "Zhicheng Chen",
                "type": "finder"
              },
              {
                "name": "Daniel Stenberg",
                "type": "remediation developer"
              }
            ],
            "database_specific": {
              "CWE": {
                "desc": "Authentication Bypass by Primary Weakness",
                "id": "CWE-305"
              },
              "URL": "https://curl.se/docs/CVE-2026-1965.json",
              "affects": "both",
              "last_affected": "8.18.0",
              "package": "curl",
              "severity": "Medium",
              "www": "https://curl.se/docs/CVE-2026-1965.html"
            },
            "details": "libcurl can in some circumstances reuse the wrong connection when asked to do\nan Negotiate-authenticated HTTP or HTTPS request.\n\nlibcurl features a pool of recent connections so that subsequent requests can\nreuse an existing connection to avoid overhead.\n\nWhen reusing a connection a range of criterion must first be met. Due to a\nlogical error in the code, a request that was issued by an application could\nwrongfully reuse an existing connection to the same server that was\nauthenticated using different credentials. One underlying reason being that\nNegotiate sometimes authenticates *connections* and not *requests*, contrary\nto how HTTP is designed to work.\n\nAn application that allows Negotiate authentication to a server (that responds\nwanting Negotiate) with `user1:password1` and then does another operation to\nthe same server also using Negotiate but with `user2:password2` (while the\nprevious connection is still alive) - the second request wrongly reused the\nsame connection and since it then sees that the Negotiate negotiation is\nalready made, it sends the request over that connection thinking it uses\nthe user2 credentials when it is in fact still using the connection\nauthenticated for user1...\n\nThe set of authentication methods to use is set with `CURLOPT_HTTPAUTH`.\n\nApplications can disable libcurl\u0027s reuse of connections and thus mitigate this\nproblem, by using one of the following libcurl options to alter how\nconnections are or are not reused: `CURLOPT_FRESH_CONNECT`,\n`CURLOPT_MAXCONNECTS` and `CURLMOPT_MAX_HOST_CONNECTIONS` (if using the\ncurl_multi API).",
            "id": "CURL-CVE-2026-1965",
            "modified": "2026-09-07T10:34:51.00Z",
            "published": "2026-03-11T08:00:00.00Z",
            "schema_version": "1.5.0",
            "summary": "bad reuse of HTTP Negotiate connection"
          }
        }
      },
      "cveMetadata": {
        "assignerOrgId": "2499f714-1537-4658-8207-48ae4bb9eae9",
        "assignerShortName": "curl",
        "cveId": "CVE-2026-1965",
        "datePublished": "2026-03-11T10:08:52.431Z",
        "dateReserved": "2026-02-05T11:00:50.882Z",
        "dateUpdated": "2026-09-15T06:02:49.175Z",
        "state": "PUBLISHED"
      },
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

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Detection rules are retrieved from Rulezet.

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Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.


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