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GHSA-3WWX-PV8P-Q78V

Vulnerability from github – Published: 2026-09-28 21:42 – Updated: 2026-09-28 21:42

Summary

undici vulnerable to Denial of Service via unhandled error in WebSocket permessage-deflate decompression

Details

Impact

undici's WebSocket client (including Node.js's bundled globalThis.WebSocket) crashes the entire Node.js process when a remote WebSocket peer sends a permessage-deflate compressed message that crosses the decompressed-payload size limit and then contains a malformed DEFLATE block. In lib/web/websocket/permessage-deflate.js, the size-limit cleanup calls removeAllListeners() on the internal zlib InflateRaw, removing its error listener, but leaves the stream running. The inflater then emits a Z_DATA_ERROR with no listener attached, which Node.js treats as a fatal unhandled error event and terminates the process. Application error/close handlers on the public WebSocket cannot observe or prevent this, because the failing object is the internal InflateRaw.

A malicious or compromised WebSocket server can crash a client with a single connection, unauthenticated and without any application mistake. The attack is asymmetric (about 130 KB on the wire expands past the limit) and can be repeated on reconnect (crash loop).

Affected applications are those using the undici WebSocket client (new WebSocket(...)) or Node.js's bundled globalThis.WebSocket that can be induced to connect to an attacker-controlled or compromised WebSocket endpoint.

Patches

Upgrade to undici v6.28.1, v7.29.1 or v8.10.2.

Workarounds

No workaround is available.

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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{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "undici"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "6.25.0"
            },
            {
              "fixed": "6.28.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "npm",
        "name": "undici"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "7.28.0"
            },
            {
              "fixed": "7.29.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "npm",
        "name": "undici"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "8.1.0"
            },
            {
              "fixed": "8.10.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-85024"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-248"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-09-28T21:42:37Z",
    "nvd_published_at": "2026-09-04T17:17:02Z",
    "severity": "MODERATE"
  },
  "details": "## Impact\n\nundici\u0027s WebSocket client (including Node.js\u0027s bundled `globalThis.WebSocket`) crashes the entire Node.js process when a remote WebSocket peer sends a permessage-deflate compressed message that crosses the decompressed-payload size limit and then contains a malformed DEFLATE block. In `lib/web/websocket/permessage-deflate.js`, the size-limit cleanup calls `removeAllListeners()` on the internal zlib `InflateRaw`, removing its `error` listener, but leaves the stream running. The inflater then emits a `Z_DATA_ERROR` with no listener attached, which Node.js treats as a fatal unhandled `error` event and terminates the process. Application `error`/`close` handlers on the public WebSocket cannot observe or prevent this, because the failing object is the internal `InflateRaw`.\n\nA malicious or compromised WebSocket server can crash a client with a single connection, unauthenticated and without any application mistake. The attack is asymmetric (about 130 KB on the wire expands past the limit) and can be repeated on reconnect (crash loop).\n\nAffected applications are those using the undici WebSocket client (`new WebSocket(...)`) or Node.js\u0027s bundled `globalThis.WebSocket` that can be induced to connect to an attacker-controlled or compromised WebSocket endpoint.\n\n## Patches\n\nUpgrade to undici v6.28.1, v7.29.1 or v8.10.2.\n\n## Workarounds\n\nNo workaround is available.",
  "id": "GHSA-3wwx-pv8p-q78v",
  "modified": "2026-09-28T21:42:37Z",
  "published": "2026-09-28T21:42:37Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/nodejs/undici/security/advisories/GHSA-3wwx-pv8p-q78v"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-85024"
    },
    {
      "type": "WEB",
      "url": "https://github.com/nodejs/undici/commit/07c60d9c7099a910451244afe42861bbdbdd974c"
    },
    {
      "type": "WEB",
      "url": "https://github.com/nodejs/undici/commit/4411a238a98e8791da5fff10cc9e3578a7668ed6"
    },
    {
      "type": "WEB",
      "url": "https://github.com/nodejs/undici/commit/63cf698b611fecc6ee0a17b185b930051e4b982f"
    },
    {
      "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:H/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "undici vulnerable to Denial of Service via unhandled error in WebSocket permessage-deflate decompression"
}

CVE-2026-85024 (GCVE-0-2026-85024)

Vulnerability from cvelistv5 – Published: 2026-09-04 16:20 – Updated: 2026-09-04 19:30

Title

undici vulnerable to Denial of Service via unhandled error in WebSocket permessage-deflate decompression

Summary

undici bundles a WebSocket client whose permessage-deflate size-limit cleanup removes all listeners from the internal zlib inflate stream, including its error listener, while that stream can still emit. When a remote peer sends a compressed payload that crosses the built-in 128 MiB decompressed-payload limit and then contains a malformed DEFLATE byte, the inflate stream emits a data error with no listener attached, which Node.js treats as a fatal unhandled error and terminates the entire process. Exploitation is remote and unauthenticated, requires no application mistake, and is asymmetric, since roughly 130 KB on the wire expands past the limit and crashes the process, and reconnecting can repeat the crash. This affects undici versions from 6.25.0 up to 6.28.1, from 7.28.0 up to 7.29.1, and from 8.1.0 up to 8.10.2. Users should upgrade to undici 6.28.1, 7.29.1, or 8.10.2.

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 2026-09-04 19:30 UTC

CWE

CWE-248 - Uncaught Exception

Assigner

openjs redhat root

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: 6.25.0 , < 6.28.1 (semver) Unaffected: 6.28.1 (semver) Affected: 7.28.0 , < 7.29.1 (semver) Unaffected: 7.29.1 (semver) Affected: 8.1.0 , < 8.10.2 (semver) Unaffected: 8.10.2 (semver)

Credits

mcollina krsecu UlisesGascon

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JSON

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