GHSA-q2hr-2g5m-vwhr: brace-expansion (CVE-2026-102277)

Package	Ecosystem	Affected	Fixed in
brace-expansion	npm	>=4.0.0, <5.0.12 \|\| >=3.0.0, <3.0.9 \|\| >=2.0.0, <2.1.7 \|\| <1.1.21	5.0.12, 3.0.9, 2.1.7, 1.1.21

Machine-written summary

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

Versions of the npm package brace-expansion below 1.1.21, from 2.0.0 up to but not including 2.1.7, from 3.0.0 up to but not including 3.0.9, and from 4.0.0 up to but not including 5.0.12 are affected. An attacker who can supply a brace pattern that an application passes to the expand function, directly or through minimatch or glob, can cause a quadratic-time slowdown that blocks the Node.js event loop for tens of seconds, though the process recovers afterward. Upgrade to 1.1.21, 2.1.7, 3.0.9, or 5.0.12, depending on the release line in use.

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
5.3	Medium	3.1	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L	CNA (GitHub_M)

CISA KEV Not listed.
EPSS 0.0043, the 37th percentile, on 13 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.