CVE-2026-85014

undici vulnerable to Denial of Service via WebSocketStream unclean close

Workarounds

No workaround is available.

undici's WebSocketStream crashes the client process when a WebSocket connection is closed abruptly without a close handshake. On such an unclean close, the internal socket-close handler calls abort() on the writable stream even when the application holds a writer lock. Per the WHATWG Streams standard, aborting a locked stream returns a promise that rejects with a TypeError, and the handler discards that promise. The unobserved rejection surfaces as an unhandledRejection and, under Node.js's default behavior, terminates the process.

A malicious or compromised WebSocket server can crash a client with a single connection teardown (a TCP reset, a proxy teardown, or a protocol-violating frame). Affected applications are those using the WebSocketStream API and writing through a writer, which is the standard way to write.

All releases from undici 7.0.0 are affected. WebSocketStream was introduced in 7.0.0.

CVE-2026-85014 has a CVSS score of 5.9 (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 (7.29.1, 8.10.2); upgrading removes the vulnerable code path.

Kodem intelligence

Already deployed Kodem?

Upgrade to undici v7.29.1 or v8.10.2.

1. What is CVE-2026-85014? CVE-2026-85014 is a medium-severity security vulnerability in undici (npm), affecting versions >= 7.0.0, < 7.29.1. It is fixed in 7.29.1, 8.10.2.
2. How severe is CVE-2026-85014? CVE-2026-85014 has a CVSS score of 5.9 (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.
3. Which versions of undici are affected by CVE-2026-85014? undici (npm) versions >= 7.0.0, < 7.29.1 is affected.
4. Is there a fix for CVE-2026-85014? Yes. CVE-2026-85014 is fixed in 7.29.1, 8.10.2. Upgrade to this version or later.
5. Is CVE-2026-85014 exploitable, and should I be worried? Whether CVE-2026-85014 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
6. What actually determines whether CVE-2026-85014 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.
7. How do I fix CVE-2026-85014?
   • Upgrade undici to 7.29.1 or later
   • Upgrade undici to 8.10.2 or later

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