Vulnerability-Lookup

GHSA-QRXM-FQHP-JWVM

Vulnerability from github – Published: 2026-10-27 19:02 – Updated: 2026-10-27 19:02

Summary

undici vulnerable to Denial of Service via TLS 1.2 certificate-changing renegotiation

Details

Impact

undici crashes the client process when a TLS 1.2 server renegotiates after the connection is established and presents a different, CA-trusted certificate whose hostname does not match the requested host. Node.js re-runs hostname verification on the renegotiated handshake and destroys the socket with ERR_TLS_CERT_ALTNAME_INVALID. undici's established socket error handler asserted that this error code could never occur, so the peer-controlled error became an uncaught AssertionError that terminates the Node.js process. Both the HTTP/1.1 and HTTP/2 paths are affected.

A malicious or compromised HTTPS endpoint reached through undici or the global fetch() can crash the client with a single server-initiated renegotiation, taking down all in-flight requests and background work in the process. Only TLS 1.2 is affected, because TLS 1.3 does not support renegotiation. Exploitation does not require a CA compromise: the attacker controls the endpoint and can present two ordinary valid certificates, the first matching the requested URL and the second intentionally not matching it.

Patches

Upgrade to undici 6.29.1, 7.30.1, or 8.12.2.

Workarounds

Restrict outbound connections to TLS 1.3, for example by setting connect: { minVersion: 'TLSv1.3', maxVersion: 'TLSv1.3' } on the client or agent, so that renegotiation cannot occur, when the target endpoints support TLS 1.3.

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": "4.2.1"
            },
            {
              "fixed": "6.29.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "npm",
        "name": "undici"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "7.0.0"
            },
            {
              "fixed": "7.30.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "npm",
        "name": "undici"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "8.0.0"
            },
            {
              "fixed": "8.12.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-87018"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-248",
      "CWE-617"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-10-27T19:02:21Z",
    "nvd_published_at": "2026-10-15T19:17:46Z",
    "severity": "HIGH"
  },
  "details": "## Impact\n\nundici crashes the client process when a TLS 1.2 server renegotiates after the connection is established and presents a different, CA-trusted certificate whose hostname does not match the requested host. Node.js re-runs hostname verification on the renegotiated handshake and destroys the socket with `ERR_TLS_CERT_ALTNAME_INVALID`. undici\u0027s established socket error handler asserted that this error code could never occur, so the peer-controlled error became an uncaught `AssertionError` that terminates the Node.js process. Both the HTTP/1.1 and HTTP/2 paths are affected.\n\nA malicious or compromised HTTPS endpoint reached through undici or the global `fetch()` can crash the client with a single server-initiated renegotiation, taking down all in-flight requests and background work in the process. Only TLS 1.2 is affected, because TLS 1.3 does not support renegotiation. Exploitation does not require a CA compromise: the attacker controls the endpoint and can present two ordinary valid certificates, the first matching the requested URL and the second intentionally not matching it.\n\n## Patches\n\nUpgrade to undici 6.29.1, 7.30.1, or 8.12.2.\n\n## Workarounds\n\nRestrict outbound connections to TLS 1.3, for example by setting `connect: { minVersion: \u0027TLSv1.3\u0027, maxVersion: \u0027TLSv1.3\u0027 }` on the client or agent, so that renegotiation cannot occur, when the target endpoints support TLS 1.3.",
  "id": "GHSA-qrxm-fqhp-jwvm",
  "modified": "2026-10-27T19:02:21Z",
  "published": "2026-10-27T19:02:21Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/nodejs/undici/security/advisories/GHSA-qrxm-fqhp-jwvm"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-87018"
    },
    {
      "type": "WEB",
      "url": "https://github.com/nodejs/undici/commit/12cfd96c3f430897656e3edc1c5e02be8c1cd309"
    },
    {
      "type": "WEB",
      "url": "https://github.com/nodejs/undici/commit/b40fbfc0651703cf9fa9f6ced68b679f28d8bb28"
    },
    {
      "type": "WEB",
      "url": "https://github.com/nodejs/undici/commit/e257e9f8fb42eedd50727b9cf65e548c8925e4a8"
    },
    {
      "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/v6.29.1"
    },
    {
      "type": "WEB",
      "url": "https://github.com/nodejs/undici/releases/tag/v7.30.1"
    },
    {
      "type": "WEB",
      "url": "https://github.com/nodejs/undici/releases/tag/v8.12.2"
    }
  ],
  "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 TLS 1.2 certificate-changing renegotiation"
}

CVE-2026-87018 (GCVE-0-2026-87018)

Vulnerability from cvelistv5 – Published: 2026-10-15 18:38 – Updated: 2026-10-16 20:01

Title

undici vulnerable to Denial of Service via TLS 1.2 certificate-changing renegotiation

Summary

undici is an HTTP client library for Node.js. In versions 4.2.1 through 6.29.0, 7.0.0 through 7.30.0, and 8.0.0 through 8.12.1, the client process crashes when a TLS 1.2 server renegotiates after the connection is established and presents a different, CA-trusted certificate whose hostname does not match the requested host. Node.js re-runs hostname verification on the renegotiated handshake and destroys the socket with a certificate-altname error, but undici's established-socket error handler asserted that this error code could never occur, so the peer-controlled error became an uncaught assertion that terminates the Node.js process, affecting both the HTTP/1.1 and HTTP/2 paths. A malicious or compromised HTTPS endpoint reached through undici or the global fetch() can crash the client with a single server-initiated renegotiation, taking down all in-flight requests and background work in the process, and exploitation needs no CA compromise because the attacker controls the endpoint and can present two ordinary valid certificates. Only TLS 1.2 is affected, since TLS 1.3 does not support renegotiation. The issue is fixed in undici 6.29.1, 7.30.1, and 8.12.2, and users should upgrade to one of those versions or later. As a workaround, restrict outbound connections to TLS 1.3 so renegotiation cannot occur, when the target endpoints support it.

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 2026-10-16 20:01 UTC

CWE

CWE-248 - Uncaught Exception
CWE-617 - Reachable Assertion

Assigner

openjs CNA under the redhat root

CNA scorecard C 65/100 over 121 records in the last 180 days details

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: 4.2.1 , < 6.29.1 (semver) Unaffected: 6.29.1 (semver) Affected: 7.0.0 , < 7.30.1 (semver) Unaffected: 7.30.1 (semver) Affected: 8.0.0 , < 8.12.2 (semver) Unaffected: 8.12.2 (semver)

Credits

benzdeus mcollina UlisesGascon

Show details on NVD website

JSON

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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.

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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.
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