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CVE-2021-27291: Pygments vulnerable to Regular Expression Denial of Service (ReDoS)

March 29, 2021 (updated October 14, 2024)

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.

References

  • gist.github.com/b-c-ds/b1a2cc0c68a35c57188575eb496de5ce
  • github.com/advisories/GHSA-pq64-v7f5-gqh8
  • github.com/pygments/pygments
  • github.com/pygments/pygments/commit/2e7e8c4a7b318f4032493773732754e418279a14
  • github.com/pypa/advisory-database/tree/main/vulns/pygments/PYSEC-2021-141.yaml
  • lists.debian.org/debian-lts-announce/2021/03/msg00024.html
  • lists.debian.org/debian-lts-announce/2021/05/msg00003.html
  • lists.debian.org/debian-lts-announce/2021/05/msg00006.html
  • lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/GSJRFHALQ7E3UV4FFMFU2YQ6LUDHAI55
  • lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/WSLD67LFGXOX2K5YNESSWAS4AGZIJTUQ
  • nvd.nist.gov/vuln/detail/CVE-2021-27291
  • www.debian.org/security/2021/dsa-4878
  • www.debian.org/security/2021/dsa-4889

Code Behaviors & Features

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Affected versions

All versions starting from 1.1 before 2.7.4

Fixed versions

  • 2.7.4

Solution

Upgrade to version 2.7.4 or above.

Impact 7.5 HIGH

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

Learn more about CVSS

Weakness

  • CWE-400: Uncontrolled Resource Consumption

Source file

pypi/Pygments/CVE-2021-27291.yml

Spotted a mistake? Edit the file on GitLab.

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