{"id":"CVE-2026-73565","aliases":["GHSA-9mqv-5hh9-4cgg"],"url":"https://o3.security/vulnerability/CVE-2026-73565","summary":"@hono/node-server: Unauthenticated memory-leak DoS via aborted WebSocket handshake","details":"## Summary\n\nA WebSocket upgrade request to an `upgradeWebSocket` route with a missing or malformed `Sec-WebSocket-Key` header leaks memory permanently. The request's `IncomingMessage` is retained in an internal map and a pending promise is never settled, even though no connection is established. Since the route is reachable pre-handshake without authentication, an unauthenticated attacker can flood it to gradually exhaust memory.\n\n## Details\n\nThe built-in WebSocket helper cleans up its internal map only on a successful handshake or when the route guard rejects the request. When `ws` aborts the handshake because `Sec-WebSocket-Key` is missing or malformed, no `connection` event is emitted, so neither cleanup path runs and the entry is retained forever. A present-but-malformed key leaks identically, so a proxy that only checks for the header's presence does not mitigate it.\n\n## Impact\n\nAn unauthenticated attacker can flood any public `upgradeWebSocket` route with malformed-key upgrade requests, causing unbounded memory growth and eventual loss of availability. No confidentiality or integrity impact.\n\nReported by @TarPeg007.","published":"2026-08-13T17:37:28.579Z","modified":"2026-09-12T03:30:29.185010582Z","cvss":{"score":5.3,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L"},"epss":{"score":0.00388,"percentile":0.32421,"asOf":"2026-09-15"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"npm","name":"@hono/node-server","fixedVersion":"2.0.10"}],"fix":{"url":"https://github.com/honojs/node-server/commit/3a21938c418340e980cb7ffa88e78369f78392d1","label":"honojs/node-server@3a21938"},"references":[{"type":"WEB","url":"https://github.com/honojs/node-server/releases/tag/v2.0.10"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/73xxx/CVE-2026-73565.json"},{"type":"ADVISORY","url":"https://github.com/honojs/node-server/security/advisories/GHSA-9mqv-5hh9-4cgg"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-73565"},{"type":"FIX","url":"https://github.com/honojs/node-server/commit/3a21938c418340e980cb7ffa88e78369f78392d1"},{"type":"PACKAGE","url":"https://github.com/honojs/node-server"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-09-12T03:30:29.185010582Z"}}