Vulnerability-Lookup

GHSA-4MH8-R7RC-XPVC

Vulnerability from github – Published: 2026-09-30 23:53 – Updated: 2026-09-30 23:53

Summary

fastify vulnerable to Denial of Service via unhandled exception on HTTP/2 trailer responses

Details

Impact

fastify crashes with an uncaught ERR_HTTP2_INVALID_CONNECTION_HEADERS exception when a route that registers a response trailer via reply.trailer() is served over HTTP/2. Fastify unconditionally adds the Transfer-Encoding: chunked header when a trailer is set, which is forbidden on HTTP/2, so Node.js throws while serializing the response headers. The exception is not caught and becomes an uncaughtException, terminating the Node.js process.

One unauthenticated HTTP/2 request to any route that uses trailers is enough to crash the server, dropping all in-flight requests, and the request can be repeated to keep the process down. Applications are affected only when HTTP/2 is enabled (http2: true) and at least one route registers a trailer. HTTP/1.x responses are not affected.

Patches

Upgrade to fastify 5.12.5 or later.

Workarounds

Avoid registering response trailers with reply.trailer() on routes served over HTTP/2 until upgrading.

Severity

5.9 (Medium)


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

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JSON

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{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "fastify"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "5.12.5"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-92081"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-248"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-09-30T23:53:44Z",
    "nvd_published_at": "2026-09-16T09:17:10Z",
    "severity": "MODERATE"
  },
  "details": "### Impact\n\n`fastify` crashes with an uncaught `ERR_HTTP2_INVALID_CONNECTION_HEADERS` exception when a route that registers a response trailer via `reply.trailer()` is served over HTTP/2. Fastify unconditionally adds the `Transfer-Encoding: chunked` header when a trailer is set, which is forbidden on HTTP/2, so Node.js throws while serializing the response headers. The exception is not caught and becomes an uncaughtException, terminating the Node.js process.\n\nOne unauthenticated HTTP/2 request to any route that uses trailers is enough to crash the server, dropping all in-flight requests, and the request can be repeated to keep the process down. Applications are affected only when HTTP/2 is enabled (`http2: true`) and at least one route registers a trailer. HTTP/1.x responses are not affected.\n\n### Patches\n\nUpgrade to `fastify` `5.12.5` or later.\n\n### Workarounds\n\nAvoid registering response trailers with `reply.trailer()` on routes served over HTTP/2 until upgrading.",
  "id": "GHSA-4mh8-r7rc-xpvc",
  "modified": "2026-09-30T23:53:44Z",
  "published": "2026-09-30T23:53:44Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/fastify/fastify/security/advisories/GHSA-4mh8-r7rc-xpvc"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-92081"
    },
    {
      "type": "WEB",
      "url": "https://github.com/fastify/fastify/issues/6574"
    },
    {
      "type": "WEB",
      "url": "https://github.com/fastify/fastify/commit/ad06a4c3fe8a944a904f38068249b18b8f552e90"
    },
    {
      "type": "WEB",
      "url": "https://cna.openjsf.org/security-advisories.html"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/fastify/fastify"
    },
    {
      "type": "WEB",
      "url": "https://github.com/fastify/fastify/releases/tag/v5.12.5"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "fastify vulnerable to Denial of Service via unhandled exception on HTTP/2 trailer responses"
}

CVE-2026-92081 (GCVE-0-2026-92081)

Vulnerability from cvelistv5 – Published: 2026-09-16 08:52 – Updated: 2026-09-16 14:00

Title

fastify vulnerable to Denial of Service via unhandled exception on HTTP/2 trailer responses

Summary

fastify is a fast and low-overhead web framework for Node.js. In versions before 5.12.5, when a route registers a response trailer via reply.trailer() and is served over HTTP/2, fastify unconditionally sets the Transfer-Encoding: chunked header, which is forbidden on HTTP/2, so Node.js throws while serializing the response headers. The exception is not caught and becomes an uncaughtException, so a single unauthenticated HTTP/2 request to any route that uses trailers crashes the server process and drops all in-flight requests, and it can be repeated on every restart. The issue is fixed in fastify 5.12.5, and users should upgrade to 5.12.5 or later. As a workaround, avoid registering response trailers with reply.trailer() on routes served over HTTP/2 until upgrading.

Severity

5.9 (Medium)


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

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-09-16 14:00 UTC

CWE

CWE-248 - Uncaught Exception

Assigner

openjs redhat root

References

2 references

URL	Tags
https://github.com/fastify/fastify/security/advis…
https://cna.openjsf.org/security-advisories.html

Impacted products

1 product

Vendor	Product	Version
fastify	fastify	Affected: 0 , < 5.12.5 (semver) Unaffected: 5.12.5 (semver)

Credits

mcollina UlisesGascon zerovulnlabs

Show details on NVD website

JSON

To clipboard

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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.

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