Description
The brace-expansion library generates arbitrary strings containing a common prefix and suffix. Prior to 1.1.21, 2.1.7, 3.0.9, and 5.0.12, the expand function handles untrusted {a},b}-shaped patterns with many trailing closing braces by restarting its scan once for each trailing closing brace. The successive full-input rescans with linear working-string growth cause quadratic CPU time and memory pressure that can block the Node.js event loop. The process eventually recovers, making the impact a recoverable CPU denial of service. This issue is fixed in versions 1.1.21, 2.1.7, 3.0.9, and 5.0.12.
References5
- github.com/juliangruber/brace-expansion/commit/33a5ef17b8d800bb…
- github.com/juliangruber/brace-expansion/commit/bdff773f98e59886…
- github.com/juliangruber/brace-expansion/commit/c55e67d8d8b1c56a…
- github.com/juliangruber/brace-expansion/commit/ffdfa3e3806bed17…
- github.com/juliangruber/brace-expansion/security/advisories/GHS…
Metrics
- CVSS 3.1
-
5.3
MEDIUM
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L - EPSS — exploit probability
- 0% percentile: 37 · as of 9 November 2026
- CWE
- CWE-400CWE-407
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.