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GHSA-RFGV-XXQX-MFG5

Vulnerability from github – Published: 2026-09-29 18:21 – Updated: 2026-09-29 18:21

Summary

undici vulnerable to Denial of Service via unrequested WebSocket subprotocol

Details

Impact

The undici WebSocket client throws an uncaught TypeError during the opening handshake when a server's 101 response includes a Sec-WebSocket-Protocol header that the client never requested. The throw occurs in a queueMicrotask callback with no surrounding try/catch, so it propagates as an uncaught exception and terminates the Node.js process. This is a remote, unauthenticated denial of service against any application that opens a WebSocket to an attacker controlled or compromised server, or over a plaintext ws:// connection subject to a machine-in-the-middle. It affects the default new WebSocket(url) usage, where no subprotocol is requested. Per RFC 6455 section 4.1, an unrequested subprotocol must fail the connection, not crash it.

All releases starting at undici 6.7.0 are affected.

Patches

Upgrade to undici 6.28.1, 7.29.1, or 8.10.2.

Workarounds

No workaround is available. The fix must be applied through an upgrade.

Severity

7.5 (High)


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

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{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "undici"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "6.7.0"
            },
            {
              "fixed": "6.28.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "npm",
        "name": "undici"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "7.0.0"
            },
            {
              "fixed": "7.29.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "npm",
        "name": "undici"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "8.0.0"
            },
            {
              "fixed": "8.10.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-19534"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-248",
      "CWE-252"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-09-29T18:21:33Z",
    "nvd_published_at": "2026-09-04T18:17:51Z",
    "severity": "HIGH"
  },
  "details": "### Impact\n\nThe undici WebSocket client throws an uncaught `TypeError` during the opening handshake when a server\u0027s `101` response includes a `Sec-WebSocket-Protocol` header that the client never requested. The throw occurs in a `queueMicrotask` callback with no surrounding `try`/`catch`, so it propagates as an uncaught exception and terminates the Node.js process. This is a remote, unauthenticated denial of service against any application that opens a WebSocket to an attacker controlled or compromised server, or over a plaintext `ws://` connection subject to a machine-in-the-middle. It affects the default `new WebSocket(url)` usage, where no subprotocol is requested. Per RFC 6455 section 4.1, an unrequested subprotocol must fail the connection, not crash it.\n\nAll releases starting at undici 6.7.0 are affected.\n\n### Patches\n\nUpgrade to undici 6.28.1, 7.29.1, or 8.10.2.\n\n### Workarounds\n\nNo workaround is available. The fix must be applied through an upgrade.",
  "id": "GHSA-rfgv-xxqx-mfg5",
  "modified": "2026-09-29T18:21:33Z",
  "published": "2026-09-29T18:21:33Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/nodejs/undici/security/advisories/GHSA-rfgv-xxqx-mfg5"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-19534"
    },
    {
      "type": "WEB",
      "url": "https://github.com/nodejs/undici/commit/2af0faf88b906d3127a360c3ac75164c0f95e5a5"
    },
    {
      "type": "WEB",
      "url": "https://github.com/nodejs/undici/commit/6615e0175e9b635bcd2e3e87a47daa82f6f5b728"
    },
    {
      "type": "WEB",
      "url": "https://github.com/nodejs/undici/commit/66e12816064cf3068f63bd134748b7fc4e779bad"
    },
    {
      "type": "WEB",
      "url": "https://cna.openjsf.org/security-advisories.html"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/nodejs/undici"
    },
    {
      "type": "WEB",
      "url": "https://github.com/nodejs/undici/releases/tag/v6.28.1"
    },
    {
      "type": "WEB",
      "url": "https://github.com/nodejs/undici/releases/tag/v7.29.1"
    },
    {
      "type": "WEB",
      "url": "https://github.com/nodejs/undici/releases/tag/v8.10.2"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "undici vulnerable to Denial of Service via unrequested WebSocket subprotocol"
}

CVE-2026-19534 (GCVE-0-2026-19534)

Vulnerability from cvelistv5 – Published: 2026-09-04 17:10 – Updated: 2026-09-04 18:18

Title

undici vulnerable to Denial of Service via unrequested WebSocket subprotocol

Summary

undici's WebSocket client crashes the whole Node.js process during the opening handshake when a server responds with a subprotocol that the client never requested. A default WebSocket connection sends no subprotocol, but if the server's 101 response includes a Sec-WebSocket-Protocol header, undici dereferences a null value while checking it against the requested list and throws an uncaught TypeError. Because that code runs inside a microtask with no surrounding error handling, the exception propagates and terminates the process under Node's default behavior, instead of gracefully failing the connection as required by the WebSocket protocol. Any application that opens a WebSocket to an attacker-controlled or compromised server, or over a plaintext connection subject to a machine-in-the-middle, can be crashed remotely without authentication in the default configuration. This affects undici versions from 6.7.0 up to 6.28.1, from 7.0.0 up to 7.29.1, and from 8.0.0 up to 8.10.2. Users should upgrade to undici 6.28.1, 7.29.1, or 8.10.2.

Severity

7.5 (High)


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

SSVC

Exploitation: none Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-09-04 18:18 UTC

CWE

CWE-248 - Uncaught Exception
CWE-252 - Unchecked Return Value

Assigner

openjs redhat root Scorecard

References

2 references

URL	Tags
https://github.com/nodejs/undici/security/advisor…
https://cna.openjsf.org/security-advisories.html

Impacted products

1 product

Vendor	Product	Version
undici	undici	Affected: 6.7.0 , < 6.28.1 (semver) Unaffected: 6.28.1 (semver) Affected: 7.0.0 , < 7.29.1 (semver) Unaffected: 7.29.1 (semver) Affected: 8.0.0 , < 8.10.2 (semver) Unaffected: 8.10.2 (semver)

Credits

manus-use mcollina UlisesGascon

Show details on NVD website

JSON

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Sightings

Author	Source	Type	Date	Other

Nomenclature

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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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