{"id":"CVE-2026-2229","aliases":["GHSA-v9p9-hfj2-hcw8"],"url":"https://o3.security/vulnerability/CVE-2026-2229","summary":"undici is vulnerable to Unhandled Exception in undici WebSocket Client Due to Invalid server_max_window_bits Validation","details":"ImpactThe 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\n  *  The isValidClientWindowBits() function only validates that the value contains ASCII digits, not that it falls within the valid range 8-15\n  *  The createInflateRaw() call is not wrapped in a try-catch block\n  *  The resulting exception propagates up through the call stack and crashes the Node.js process","published":"2026-03-12T20:27:05.600Z","modified":"2026-09-15T03:48:10.495184200Z","cvss":{"score":7.5,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"npm","name":"undici","fixedVersion":"6.24.0"},{"ecosystem":"npm","name":"undici","fixedVersion":"7.24.0"}],"fix":null,"references":[{"type":"WEB","url":"https://datatracker.ietf.org/doc/html/rfc7692"},{"type":"WEB","url":"https://github.com/nodejs/undici/"},{"type":"WEB","url":"https://hackerone.com/reports/3487486"},{"type":"WEB","url":"https://nodejs.org/api/zlib.html#class-zlibinflateraw"},{"type":"WEB","url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-2229.json"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:13826"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:17789"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:21772"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:21931"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:34342"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:56431"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:5807"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:7080"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:7123"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:7302"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:7310"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:7350"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:7670"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:7675"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:7983"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:9742"},{"type":"ADVISORY","url":"https://access.redhat.com/security/cve/CVE-2026-2229"},{"type":"ADVISORY","url":"https://cna.openjsf.org/security-advisories.html"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/2xxx/CVE-2026-2229.json"},{"type":"ADVISORY","url":"https://github.com/nodejs/undici/security/advisories/GHSA-v9p9-hfj2-hcw8"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-2229"},{"type":"REPORT","url":"https://bugzilla.redhat.com/show_bug.cgi?id=2447143"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-09-15T03:48:10.495184200Z"}}