CVE catalog

CVE-2026-109855

undici is an HTTP client library for Node.js. In…

[CVE catalog]

undici is an HTTP client library for Node.js. In versions 8.11.0 and 8.11.1, its experimental WebSocket client, which is enabled by default when HTTP/2 is allowed, mishandles a failed WebSocket handshake over HTTP/2: the request is already marked completed, so the abort becomes a no-op and the underlying HTTP/2 stream is left open with no error listener. When a malicious server then destroys the connection, the orphaned stream emits an unhandled error and the Node.js process exits. A remote, unauthenticated server can therefore crash any client that opens a WebSocket to it over HTTP/2, resulting in a denial of service. The issue is fixed in undici 8.11.2, and users should upgrade to 8.11.2 or later. As a workaround, set allowH2 to false to disable HTTP/2 for WebSocket connections, or avoid opening WebSocket connections to untrusted servers.

Severity
High · CVSS 7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Published
Updated
Source
[NVD] · [CVE record]
EPSS
0.28% · Oct 27, 2026

Projects and upstream resources

Reported versions and fixes

Each observation applies to its named package, distribution, and release. Distribution backports can fix a vulnerability while retaining an older upstream version number.

Version impact has not been established. The original provider fields are retained below.

Provider details and historical evidence
Original provider fields
{
  "package_releases": [
    {
      "name": "node-undici",
      "status": "fixed",
      "release": "sid",
      "version": "8.12.2+dfsg+~cs3.2.3-2"
    },
    {
      "name": "node-undici",
      "status": "vulnerable",
      "release": "forky",
      "version": "8.10.2+dfsg+~cs3.2.2-1"
    },
    {
      "name": "node-undici",
      "status": "not affected",
      "release": "trixie",
      "version": "7.3.0+dfsg1+~cs24.12.11-1"
    },
    {
      "name": "node-undici",
      "status": "not affected",
      "release": "bookworm",
      "version": "5.15.0+dfsg1+~cs20.10.9.3-1+deb12u4"
    },
    {
      "name": "node-undici",
      "status": "not affected",
      "release": "bookworm-security",
      "version": "5.15.0+dfsg1+~cs20.10.9.3-1+deb12u3"
    }
  ],
  "fixed_versions": [
    {
      "bug": null,
      "name": "node-undici",
      "type": "source",
      "origin": null,
      "release": "sid",
      "urgency": "not yet assigned",
      "fixed_version": "8.12.2+dfsg+~cs3.2.3-1"
    },
    {
      "bug": null,
      "name": "node-undici",
      "type": "source",
      "origin": null,
      "release": "forky",
      "urgency": "not yet assigned",
      "fixed_version": ""
    },
    {
      "bug": null,
      "name": "node-undici",
      "type": "source",
      "origin": null,
      "release": "trixie",
      "urgency": "unimportant",
      "fixed_version": "0"
    },
    {
      "bug": null,
      "name": "node-undici",
      "type": "source",
      "origin": null,
      "release": "bookworm",
      "urgency": "unimportant",
      "fixed_version": "0"
    }
  ],
  "distribution_packages": [
    {
      "name": "undici",
      "ranges": [
        {
          "fixed": "8.11.2",
          "introduced": "8.11.0",
          "last_affected": "",
          "start_excluding": ""
        }
      ],
      "ecosystem": "cpe",
      "fixed_version": "8.11.2",
      "provider_record_id": "NVD-CVE-2026-109855"
    }
  ]
}

OpenFactory catalog packages

Matching against OpenFactory catalog package versions is in progress.

[Debian 12 (Bookworm)]

  • [node-llhttp]Unknown

    Source package: [node-undici]

    Details (4)

    • 8.1.0~5.15.0+dfsg1+~cs20.10.9.3-1+deb12u4 · all · bookworm

      Not affected

      nvd · node-undici · debian · bookworm

    • 8.1.0~5.15.0+dfsg1+~cs20.10.9.3-1+deb12u4 · all · bookworm

      Not affected

      nvd · node-undici · debian · bookworm

    • 8.1.0~5.15.0+dfsg1+~cs20.10.9.3-1+deb12u3 · all · bookworm-security

      Not affected

      nvd · node-undici · debian · bookworm

    • 8.1.0~5.15.0+dfsg1+~cs20.10.9.3-1+deb12u3 · all · bookworm-security

      Not affected

      nvd · node-undici · debian · bookworm

  • [node-undici]Unknown
    Details (4)

    • 5.15.0+dfsg1+~cs20.10.9.3-1+deb12u4 · all · bookworm

      Not affected

      nvd · node-undici · debian · bookworm

    • 5.15.0+dfsg1+~cs20.10.9.3-1+deb12u4 · all · bookworm

      Not affected

      nvd · node-undici · debian · bookworm

    • 5.15.0+dfsg1+~cs20.10.9.3-1+deb12u3 · all · bookworm-security

      Not affected

      nvd · node-undici · debian · bookworm

    • 5.15.0+dfsg1+~cs20.10.9.3-1+deb12u3 · all · bookworm-security

      Not affected

      nvd · node-undici · debian · bookworm

Observed:

References

[Debian Security Tracker] · [FIRST EPSS] · [National Vulnerability Database (NVD)] · [OSV Package Vulnerability Database] · [Red Hat security advisories and VEX]