Vulnerability-Lookup

CVE-2026-9546 (GCVE-0-2026-9546)

Vulnerability from cvelistv5 – Published: 2026-07-03 06:18 – Updated: 2026-09-15 06:03

Title

sending old referer

Summary

A vulnerability in libcurl caused the HTTP `Referer:` header to persist even when explicitly cleared. While the documentation states that passing NULL to `CURLOPT_REFERER` suppresses the header, the option failed to clear the internal state. As a result, the previous referrer string was erroneously reused and sent in subsequent requests, potentially leaking sensitive information to unintended servers.

Severity

7.5 (High)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

SSVC

Exploitation: poc Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-07-06 16:51 UTC

CWE

CWE-200 - Exposure of Sensitive Information to an Unauthorized Actor

Assigner

curl redhat root

References

3 references

URL	Tags
https://curl.se/docs/CVE-2026-9546.json
https://curl.se/docs/CVE-2026-9546.html
https://hackerone.com/reports/3754343

Impacted products

3 products

Vendor	Product	Version
curl	curl	Affected: 8.18.0 , < 8.20.1 (semver)
curl	curl	Affected: 2cb868242dc2ac9cd52ee64987ef51d5964a56f9 , < 862e8a74a84478d82973471b4f49dc2746c1780e (git)
curl	curl	Affected: 8.20.0 Affected: 8.19.0 Affected: 8.18.0

Credits

renjian on hackerone Daniel Stenberg

Show details on NVD website

JSON

To clipboard

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BELL-CVE-2026-9546 (CVE-2026-9546)

Vulnerability from osv_bellsoft – Published: 2026-07-02 17:40 – Updated: 2026-07-06 18:03 – Source website

Severity

7.5 (High)


                    
                      CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

References

URL

Type

https://docs.bell-sw.com/security/cves/CVE-2026-9546

ADVISORY

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "Alpaquita:23",
        "name": "curl",
        "purl": "pkg:apk/alpaquita/curl?arch=source\u0026distro=23"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "8.1.0-r2"
            },
            {
              "fixed": "8.21.0-r0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Alpaquita:25",
        "name": "curl",
        "purl": "pkg:apk/alpaquita/curl?arch=source\u0026distro=25"
      },
      "ranges": [
        {
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            {
              "introduced": "8.14.0-r1"
            },
            {
              "fixed": "8.21.0-r0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Alpaquita:stream",
        "name": "curl",
        "purl": "pkg:apk/alpaquita/curl?arch=source\u0026distro=stream"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "8.1.2-r0"
            },
            {
              "fixed": "8.21.0-r0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "BellSoft Hardened Containers:stream",
        "name": "curl",
        "purl": "pkg:apk/bellsoft-hardened-containers/curl?arch=source\u0026distro=stream"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "8.1.2-r0"
            },
            {
              "fixed": "8.21.0-r0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "id": "BELL-CVE-2026-9546",
  "modified": "2026-07-06T18:03:31.476489Z",
  "published": "2026-07-02T17:40:11.949982Z",
  "references": [
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      "url": "https://docs.bell-sw.com/security/cves/CVE-2026-9546"
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    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
      "type": "CVSS_V3"
    }
  ],
  "upstream": [
    "CVE-2026-9546"
  ]
}

CERTFR-2026-AVI-0797

Vulnerability from certfr_avis - Published: 2026-06-24 - Updated: 2026-06-24

De multiples vulnérabilités ont été découvertes dans cURL et libcurl. Certaines d'entre elles permettent à un attaquant de provoquer un déni de service à distance, une atteinte à la confidentialité des données et un contournement de la politique de sécurité.

Solutions

Se référer au bulletin de sécurité de l'éditeur pour l'obtention des correctifs (cf. section Documentation).

Impacted products

	Vendor	Product	Description
	Curl	cURL et libcurl	cURL et libcurl versions antérieures à 8.21.0

References

Title

Publication Time

FKIE_CVE-2026-9546

Vulnerability from fkie_nvd - Published: 2026-07-03 07:16 - Updated: 2026-09-15 07:16

Severity

7.5 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Summary

References

URL	Tags
2499f714-1537-4658-8207-48ae4bb9eae9	https://curl.se/docs/CVE-2026-9546.html	Patch, Vendor Advisory
2499f714-1537-4658-8207-48ae4bb9eae9	https://curl.se/docs/CVE-2026-9546.json	Third Party Advisory
2499f714-1537-4658-8207-48ae4bb9eae9	https://hackerone.com/reports/3754343	Exploit, Issue Tracking, Third Party Advisory
134c704f-9b21-4f2e-91b3-4a467353bcc0	https://hackerone.com/reports/3754343	Exploit, Issue Tracking, Third Party Advisory

Impacted products

	Vendor	Product	Version
	haxx	curl	*

JSON

To clipboard

{
  "affected": [
    {
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          "product": "curl",
          "vendor": "curl",
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    }
  ],
  "configurations": [
    {
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        {
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            {
              "criteria": "cpe:2.3:a:haxx:curl:*:*:*:*:*:*:*:*",
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              "versionEndExcluding": "8.21.0",
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            }
          ],
          "negate": false,
          "operator": "OR"
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      ]
    }
  ],
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      "value": "A vulnerability in libcurl caused the HTTP `Referer:` header to persist even\nwhen explicitly cleared. While the documentation states that passing NULL to\n`CURLOPT_REFERER` suppresses the header, the option failed to clear the\ninternal state. As a result, the previous referrer string was erroneously\nreused and sent in subsequent requests, potentially leaking sensitive\ninformation to unintended servers."
    }
  ],
  "id": "CVE-2026-9546",
  "lastModified": "2026-09-15T07:16:35.130",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 7.5,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 3.6,
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-9546",
          "options": [
            {
              "exploitation": "poc"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-07-06T16:51:06.094113Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-07-03T07:16:25.893",
  "references": [
    {
      "source": "2499f714-1537-4658-8207-48ae4bb9eae9",
      "tags": [
        "Patch",
        "Vendor Advisory"
      ],
      "url": "https://curl.se/docs/CVE-2026-9546.html"
    },
    {
      "source": "2499f714-1537-4658-8207-48ae4bb9eae9",
      "tags": [
        "Third Party Advisory"
      ],
      "url": "https://curl.se/docs/CVE-2026-9546.json"
    },
    {
      "source": "2499f714-1537-4658-8207-48ae4bb9eae9",
      "tags": [
        "Exploit",
        "Issue Tracking",
        "Third Party Advisory"
      ],
      "url": "https://hackerone.com/reports/3754343"
    },
    {
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "tags": [
        "Exploit",
        "Issue Tracking",
        "Third Party Advisory"
      ],
      "url": "https://hackerone.com/reports/3754343"
    }
  ],
  "sourceIdentifier": "2499f714-1537-4658-8207-48ae4bb9eae9",
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-200"
        }
      ],
      "source": "2499f714-1537-4658-8207-48ae4bb9eae9",
      "type": "Secondary"
    },
    {
      "description": [
        {
          "lang": "en",
          "value": "NVD-CWE-noinfo"
        }
      ],
      "source": "nvd@nist.gov",
      "type": "Primary"
    }
  ]
}

GHSA-25RX-86V8-32C6

Vulnerability from github – Published: 2026-07-03 09:31 – Updated: 2026-07-06 18:30

Details

A vulnerability in libcurl caused the HTTP Referer: header to persist even when explicitly cleared. While the documentation states that passing NULL to CURLOPT_REFERER suppresses the header, the option failed to clear the internal state. As a result the previous referrer string was erroneously reused and sent in subsequent requests, potentially leaking sensitive information to unintended servers.

Severity

7.5 (High)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Show details on source website

JSON

To clipboard

{
  "affected": [],
  "aliases": [
    "CVE-2026-9546"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-200"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-07-03T07:16:25Z",
    "severity": "HIGH"
  },
  "details": "A vulnerability in libcurl caused the HTTP `Referer:` header to persist even\nwhen explicitly cleared. While the documentation states that passing NULL to\n`CURLOPT_REFERER` suppresses the header, the option failed to clear the\ninternal state. As a result the previous referrer string was erroneously\nreused and sent in subsequent requests, potentially leaking sensitive\ninformation to unintended servers.",
  "id": "GHSA-25rx-86v8-32c6",
  "modified": "2026-07-06T18:30:50Z",
  "published": "2026-07-03T09:31:27Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-9546"
    },
    {
      "type": "WEB",
      "url": "https://hackerone.com/reports/3754343"
    },
    {
      "type": "WEB",
      "url": "https://curl.se/docs/CVE-2026-9546.html"
    },
    {
      "type": "WEB",
      "url": "https://curl.se/docs/CVE-2026-9546.json"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
      "type": "CVSS_V3"
    }
  ]
}

MSRC_CVE-2026-9546

Vulnerability from csaf_microsoft - Published: 2026-08-28 01:02 - Updated: 2026-08-28 01:02

Summary

sending old referer

Scope

1 vulnerability in this advisory, including CVE-2026-9546.

CVE-2026-9546

7.5 (High)


                
                  CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Known affected: 2 products

Open the full advisory

OPENSUSE-SU-2026:11230-1

Vulnerability from csaf_opensuse - Published: 2026-07-09 00:00 - Updated: 2026-09-17 17:13

Summary

curl-8.21.0-1.1 on GA media

Severity

Moderate

Scope

18 vulnerabilities in this advisory, including CVE-2026-9546.

CVE-2026-9546

5.3 (Medium)


                
                  CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Recommended: 36 products

Open the full advisory

RHSA-2026:29017

Vulnerability from csaf_redhat - Published: 2026-06-24 12:18 - Updated: 2026-09-29 22:30

Summary

Red Hat Security Advisory: Red Hat Hardened Images RPMs bug fix and enhancement update

Severity

Important

Scope

16 vulnerabilities in this advisory, including CVE-2026-9546.

CVE-2026-9546

A flaw was found in libcurl. This vulnerability causes the HTTP Referer header to persist even after it has been explicitly cleared. This can lead to the previous referrer string being unintentionally reused and sent in subsequent requests, potentially disclosing sensitive information to unintended servers.

7.5 (High)


                
                  CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Fixed: 3 products

https://access.redhat.com/errata/RHSA-2026:29017

Open the full advisory

RHSA-2026:34975

Vulnerability from csaf_redhat - Published: 2026-07-02 15:43 - Updated: 2026-09-29 22:30

Summary

Red Hat Security Advisory: Red Hat Hardened Images RPMs bug fix and enhancement update

Severity

Important

Scope

24 vulnerabilities in this advisory, including CVE-2026-9546.

CVE-2026-9546

7.5 (High)


                
                  CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Fixed: 4 products

https://access.redhat.com/errata/RHSA-2026:34975

Open the full advisory

UBUNTU-CVE-2026-9546 (CVE-2026-9546)

Vulnerability from osv_ubuntu – Published: 2026-06-24 14:00 – Updated: 2026-06-24 14:00 – Source website

Withdrawn 2026-06-30

Details

A vulnerability in libcurl caused the HTTP Referer: header to persist even when explicitly cleared. While the documentation states that passing NULL to CURLOPT_REFERER suppresses the header, the option failed to clear the internal state. As a result, the previous referrer string was erroneously reused and sent in subsequent requests, potentially leaking sensitive information to unintended servers.

Severity

N/A (UNKNOWN)

low

References

URL

Type

	https://ubuntu.com/security/CVE-2026-9546	REPORT
	https://www.cve.org/CVERecord?id=CVE-2026-9546	REPORT
	https://curl.se/L7HzKXisfJ/CVE-2026-9546.md	REPORT

JSON

To clipboard

{
  "affected": [
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "curl",
            "binary_version": "8.18.0-1ubuntu2.1"
          },
          {
            "binary_name": "libcurl3t64-gnutls",
            "binary_version": "8.18.0-1ubuntu2.1"
          },
          {
            "binary_name": "libcurl4t64",
            "binary_version": "8.18.0-1ubuntu2.1"
          }
        ],
        "priority_reason": "Upstream defined this as low severity"
      },
      "package": {
        "ecosystem": "Ubuntu:26.04:LTS",
        "name": "curl",
        "purl": "pkg:deb/ubuntu/curl@8.18.0-1ubuntu2.1?arch=source\u0026distro=resolute"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "8.14.1-2ubuntu1",
        "8.17.0-1ubuntu1",
        "8.18.0-1ubuntu1",
        "8.18.0-1ubuntu2",
        "8.18.0-1ubuntu2.1"
      ]
    }
  ],
  "aliases": [],
  "details": "A vulnerability in libcurl caused the HTTP `Referer:` header to persist even when explicitly cleared. While the documentation states that passing NULL to `CURLOPT_REFERER` suppresses the header, the option failed to clear the internal state. As a result, the previous referrer string was erroneously reused and sent in subsequent requests, potentially leaking sensitive information to unintended servers.",
  "id": "UBUNTU-CVE-2026-9546",
  "modified": "2026-06-24T14:00:00Z",
  "published": "2026-06-24T14:00:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2026-9546"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-9546"
    },
    {
      "type": "REPORT",
      "url": "https://curl.se/L7HzKXisfJ/CVE-2026-9546.md"
    }
  ],
  "related": [],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "low",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2026-9546"
  ],
  "withdrawn": "2026-06-30T01:55:01Z"
}

WID-SEC-W-2026-2052

Vulnerability from csaf_certbund - Published: 2026-06-23 22:00 - Updated: 2026-09-28 22:00

Summary

cURL: Mehrere Schwachstellen

Severity

Mittel

Scope

10 vulnerabilities in this advisory, including CVE-2026-9546.

CVE-2026-9546

Known affected: 14 products

Open the full advisory

Sightings

Author	Source	Type	Date	Other

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.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

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.

Action not permitted

CVE-2026-9546 (GCVE-0-2026-9546)

BELL-CVE-2026-9546 (CVE-2026-9546)

Solutions

UBUNTU-CVE-2026-9546 (CVE-2026-9546)

Tags

Sightings

Nomenclature

Related by attack behaviour