Summary
Node.js Adapter for Hono: Unauthenticated memory-leak DoS via aborted WebSocket handshake
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.
The application allocates resources such as memory, threads, or file descriptors based on untrusted input without enforcing a cap. Typical impact: resource exhaustion leading to denial of service.
GHSA-9MQV-5HH9-4CGG has a CVSS score of 5.3 (Medium). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (2.0.10); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Frequently Asked Questions
- What is GHSA-9MQV-5HH9-4CGG? GHSA-9MQV-5HH9-4CGG is a medium-severity allocation of resources without limits or throttling vulnerability in @hono/node-server (npm), affecting versions >= 2.0.0, <= 2.0.9. It is fixed in 2.0.10. The application allocates resources such as memory, threads, or file descriptors based on untrusted input without enforcing a cap.
- How severe is GHSA-9MQV-5HH9-4CGG? GHSA-9MQV-5HH9-4CGG has a CVSS score of 5.3 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of @hono/node-server are affected by GHSA-9MQV-5HH9-4CGG? @hono/node-server (npm) versions >= 2.0.0, <= 2.0.9 is affected.
- Is there a fix for GHSA-9MQV-5HH9-4CGG? Yes. GHSA-9MQV-5HH9-4CGG is fixed in 2.0.10. Upgrade to this version or later.
- Is GHSA-9MQV-5HH9-4CGG exploitable, and should I be worried? Whether GHSA-9MQV-5HH9-4CGG is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether GHSA-9MQV-5HH9-4CGG is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix GHSA-9MQV-5HH9-4CGG? Upgrade
@hono/node-serverto 2.0.10 or later.