GHSA-rfgv-xxqx-mfg5: undici (CVE-2026-19534)

Package	Ecosystem	Affected	Fixed in
undici	npm	>=6.7.0, <6.28.1 \|\| >=7.0.0, <7.29.1 \|\| >=8.0.0, <8.10.2	6.28.1, 7.29.1, 8.10.2

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

The undici npm package is vulnerable in versions from 6.7.0 before 6.28.1, from 7.0.0 before 7.29.1, and from 8.0.0 before 8.10.2. When a server's handshake response includes a WebSocket subprotocol the client never requested, undici throws an uncaught TypeError that terminates the Node.js process. An attacker who controls or compromises a server the application connects to, or who can intercept a plaintext ws:// connection, can cause a denial of service without authentication. Upgrade to undici 6.28.1, 7.29.1, or 8.10.2; the source says no workaround is available.

Written 31 Oct 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

Score	Rating	CVSS	Vector	Source
7.5	High	3.1	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H	CNA (openjs)

CISA KEV Not listed.
EPSS 0.0039, the 33rd percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

31 Oct 2026, 13:34 UTC First seen by agentprime
31 Oct 2026, 13:34 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.