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

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

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

EPSS

• CVE-2026-73565: 0.53% estimated exploitation activity in the next 30 days; percentile 44.81 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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…

Published by the source

21 Jul 2026, 22:04 UTC

Last modified by the source

13 Aug 2026, 17:55 UTC

Source last checked

26 Oct 2026, 13:01 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-9mqv-5hh9-4cgg

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-9mqv-5hh9-4cgg

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# Patch Next advisory brief: CVE-2026-73565

Advisory: Node.js Adapter for Hono: Unauthenticated memory-leak DoS via aborted WebSocket handshake
IDs: CVE-2026-73565, GHSA-9mqv-5hh9-4cgg
Record: https://patchnext.com/advisories/cve-2026-73565 (revision 2, source checked 26 Oct 2026, 13:01 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: @hono/node-server 2.0.10. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm @hono/node-server: affected >= 2.0.0, <= 2.0.9; fixed in 2.0.10

## Suggested inspection (read-only)
- `npm ls @hono/node-server --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on @hono/node-server.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-9mqv-5hh9-4cgg (OSV record GHSA-9mqv-5hh9-4cgg lists affected ranges: npm @hono/node-server >=2.0.0 <2.0.10 (fixed))
- Verified: https://github.com/advisories/GHSA-9mqv-5hh9-4cgg (GitHub-reviewed advisory GHSA-9mqv-5hh9-4cgg lists affected ranges: npm @hono/node-server >=2.0.0 <=2.0.9)

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