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Pygments vulnerable to Regular Expression Denial of Service (ReDoS)

High severity GitHub Reviewed Published Mar 29, 2021 to the GitHub Advisory Database • Updated Aug 16, 2023

Package

pip Pygments (pip)

Affected versions

>= 1.1, < 2.7.4

Patched versions

2.7.4

Description

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

Published by the National Vulnerability Database Mar 17, 2021
Reviewed Mar 22, 2021
Published to the GitHub Advisory Database Mar 29, 2021
Last updated Aug 16, 2023

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS score

0.958%
(84th percentile)

Weaknesses

CVE ID

CVE-2021-27291

GHSA ID

GHSA-pq64-v7f5-gqh8

Source code

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