Node.js Adapter for Hono: Unauthenticated memory-leak DoS via aborted WebSocket handshake

## Summary A 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. ## Details The 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. ## Impact An 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. Reported by @TarPeg007.

Source published

21 Jul 2026 22:04:27 UTC

Source modified

13 Aug 2026 17:55:56 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

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