{"id":"GHSA-rfgv-xxqx-mfg5","summary":"undici vulnerable to Denial of Service via unrequested WebSocket subprotocol","details":"### Impact\n\nThe 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.\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.","aliases":["CVE-2026-19534"],"modified":"2026-09-29T18:30:41.167602268Z","published":"2026-09-29T18:21:33Z","database_specific":{"github_reviewed":true,"github_reviewed_at":"2026-09-29T18:21:33Z","nvd_published_at":"2026-09-04T18:17:51Z","cwe_ids":["CWE-248","CWE-252"],"severity":"HIGH"},"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"}],"affected":[{"package":{"name":"undici","ecosystem":"npm","purl":"pkg:npm/undici"},"ranges":[{"type":"SEMVER","events":[{"introduced":"6.7.0"},{"fixed":"6.28.1"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/09/GHSA-rfgv-xxqx-mfg5/GHSA-rfgv-xxqx-mfg5.json"}},{"package":{"name":"undici","ecosystem":"npm","purl":"pkg:npm/undici"},"ranges":[{"type":"SEMVER","events":[{"introduced":"7.0.0"},{"fixed":"7.29.1"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/09/GHSA-rfgv-xxqx-mfg5/GHSA-rfgv-xxqx-mfg5.json"}},{"package":{"name":"undici","ecosystem":"npm","purl":"pkg:npm/undici"},"ranges":[{"type":"SEMVER","events":[{"introduced":"8.0.0"},{"fixed":"8.10.2"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/09/GHSA-rfgv-xxqx-mfg5/GHSA-rfgv-xxqx-mfg5.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"}]}