Vulnerability · Published Sep 4, 2026 · Assigned by openjs

CVE-2026-85014undici vulnerable to Denial of Service via WebSocketStream unclean close

Medium 5.9

In plain English

A medium-severity security flaw in undici from undici. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 31% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)5.9Medium
Exploit odds (30 days)0.4%top 69.2% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

undici's experimental WebSocketStream client crashes the whole Node.js process when a remote peer closes the TCP connection without a WebSocket close handshake. On an unclean close the internal socket-close handler calls abort on the writable stream unconditionally and discards the returned promise, but per the WHATWG Streams standard aborting a locked writable returns a promise that rejects with a TypeError. Because the application holds a writer on that writable, which is the only way to write, the rejection is never observed and Node's default unhandled-rejection behavior terminates the process. An untrusted server can therefore crash a client with a single abrupt disconnect, with no authentication and no application mistake. This affects undici versions from 7.0.0 up to 7.29.1 and from 8.0.0 up to 8.10.2. Users should upgrade to undici 7.29.1 or 8.10.2.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12node-undicino fix listedDEBIAN-CVE-2026-85014
Debian:13node-undicino fix listedDEBIAN-CVE-2026-85014
Debian:14node-undici8.10.2+dfsg+~cs3.2.2-1DEBIAN-CVE-2026-85014
Ubuntu:24.04:LTSnode-undicino fix listedUBUNTU-CVE-2026-85014
Ubuntu:26.04:LTSnode-undicino fix listedUBUNTU-CVE-2026-85014
Ubuntu:26.10node-undicino fix listedUBUNTU-CVE-2026-85014
npmundici8.10.2GHSA-rx4f-c7p8-82vq
npmundici7.29.1GHSA-rx4f-c7p8-82vq

Affected products (as reported)

VendorProductVersions
undici undici 7.0.0 – before 7.29.18.0.0 – before 8.10.2

Weakness: CWE-248, CWE-754 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

References