{
  "canonical_id": "undici--CVE-2026-2229",
  "system_id": "undici",
  "display_name": "Undici",
  "category": "frameworks",
  "advisory_mode": "core",
  "title": "Undici has Unhandled Exception in WebSocket Client Due to Invalid server_max_window_bits Validation",
  "summary": "### Impact\n\nThe undici WebSocket client is vulnerable to a denial-of-service attack due to improper validation of the `server_max_window_bits` parameter in the permessage-deflate extension. When a WebSocket client connects to a server, it automatically advertises support for permessage-deflate compression. A malicious server can respond with an out-of-range `server_max_window_bits` value (outside zlib's valid range of 8-15). When the server subsequently sends a compressed frame, the client attempts to create a zlib InflateRaw instance with the invalid windowBits value, causing a synchronous RangeError exception that is not caught, resulting in immediate process termination.\n\nThe vulnerability exists because:\n\n1. The `isValidClientWindowBits()` function only validates that the value contains ASCII digits, not that it falls within the valid range 8-15\n2. The `createInflateRaw()` call is not wrapped in a try-catch block\n3. The resulting exception propagates up through the call stack and crashes the Node.js process\n\n### Patches\n_Has the problem been patched? What versions should users upgrade to?_\n\n### Workarounds\n_Is there a way for users to fix or remediate the vulnerability without upgrading?_",
  "published_at": "2026-03-13T20:41:41Z",
  "updated_at": "2026-03-13T20:54:26.149214Z",
  "severity": "low",
  "cvss_score": 3.1,
  "exploit_status": "unknown",
  "source_confidence": "official",
  "official_source_url": "https://github.com/nodejs/undici/security/advisories/GHSA-v9p9-hfj2-hcw8",
  "secondary_source_urls": [
    "https://nvd.nist.gov/vuln/detail/CVE-2026-2229",
    "https://hackerone.com/reports/3487486",
    "https://cna.openjsf.org/security-advisories.html",
    "https://datatracker.ietf.org/doc/html/rfc7692",
    "https://github.com/nodejs/undici",
    "https://nodejs.org/api/zlib.html#class-zlibinflateraw"
  ],
  "aliases": [
    "CVE-2026-2229",
    "GHSA-v9p9-hfj2-hcw8"
  ],
  "cve_ids": [
    "CVE-2026-2229"
  ],
  "ghsa_ids": [
    "GHSA-v9p9-hfj2-hcw8"
  ],
  "osv_ids": [
    "GHSA-v9p9-hfj2-hcw8"
  ],
  "affected_versions": [
    "introduced=0, fixed<6.24.0",
    "introduced=7.0.0, fixed<7.24.0"
  ],
  "fixed_versions": [
    "6.24.0",
    "7.24.0"
  ],
  "package_name": "undici",
  "render_markdown": true,
  "case_path": "07-framework-security/frameworks/undici/cases/undici-cve-2026-2229.md",
  "secure_code_topics": [
    "ssrf-url-validation",
    "proxy-trust-boundary",
    "plugin-extension-trust-policy"
  ],
  "status": "generated",
  "triage_reasons": [],
  "metadata": {
    "source_names": [
      "OSV Undici"
    ],
    "source_kinds": [
      "osv-batch"
    ],
    "candidate_count": 1
  }
}