CVE-2021-27291

In pygments 1.1+, fixed in 2.7.4, the lexers used to parse programming languages rely heavily on regular expressions. Some of the regular expressions have exponential or cubic worst-case complexity and are vulnerable to ReDoS. By crafting malicious input, an attacker can cause a denial of service.

• CWE-1333

• https://gist.github.com/b-c-ds/b1a2cc0c68a35c57188575eb496de5ceExploit, Third Party Advisory
• https://github.com/pygments/pygments/commit/2e7e8c4a7b318f4032493773732754e418279a14Patch, Third Party Advisory
• https://lists.debian.org/debian-lts-announce/2021/03/msg00024.htmlMailing List, Third Party Advisory
• https://lists.debian.org/debian-lts-announce/2021/05/msg00003.htmlMailing List, Third Party Advisory
• https://lists.debian.org/debian-lts-announce/2021/05/msg00006.htmlMailing List, Third Party Advisory
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/GSJRFHALQ7E3UV4FFMFU2YQ6LUDHAI55/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WSLD67LFGXOX2K5YNESSWAS4AGZIJTUQ/
• https://www.debian.org/security/2021/dsa-4878Third Party Advisory
• https://www.debian.org/security/2021/dsa-4889Third Party Advisory
• https://gist.github.com/b-c-ds/b1a2cc0c68a35c57188575eb496de5ceExploit, Third Party Advisory
• https://github.com/pygments/pygments/commit/2e7e8c4a7b318f4032493773732754e418279a14Patch, Third Party Advisory
• https://lists.debian.org/debian-lts-announce/2021/03/msg00024.htmlMailing List, Third Party Advisory
• https://lists.debian.org/debian-lts-announce/2021/05/msg00003.htmlMailing List, Third Party Advisory
• https://lists.debian.org/debian-lts-announce/2021/05/msg00006.htmlMailing List, Third Party Advisory
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/GSJRFHALQ7E3UV4FFMFU2YQ6LUDHAI55/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WSLD67LFGXOX2K5YNESSWAS4AGZIJTUQ/
• https://www.debian.org/security/2021/dsa-4878Third Party Advisory
• https://www.debian.org/security/2021/dsa-4889Third Party Advisory

Published

Mar 17, 2021

Last Modified

Jun 17, 2026

Status

Modified

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