GHSA-4qv8-2p9j-2685: undici (CVE-2026-109924)

Package	Ecosystem	Affected	Fixed in
undici	npm	>=6.5.0, <6.29.1 \|\| >=7.0.0, <7.30.1 \|\| >=8.0.0, <8.12.2	6.29.1, 7.30.1, 8.12.2

Machine-written summary

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

The undici package, in the npm versions from 6.5.0 before 6.29.1, from 7.0.0 before 7.30.1, and from 8.0.0 before 8.12.2, can exhaust process memory through its EventSource client. An attacker who is a malicious or compromised Server-Sent Events peer and whom the application connects to can send many tiny data fields or a long unfinished line, which the parser retains without bound, causing denial of service. Upgrade to 6.29.1, 7.30.1, or 8.12.2, which bound this parser state; the source lists no workarounds.

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
5.9	Medium	3.1	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H	CNA (openjs)

CISA KEV Not listed.
EPSS 0.0032, the 25th percentile, on 7 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

31 Oct 2026, 13:33 UTC First seen by agentprime
31 Oct 2026, 13:33 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.