CVE Vulnerabilities

CVE-2021-39933

Inefficient Regular Expression Complexity

Published: Dec 13, 2021 | Modified: Aug 08, 2023
CVSS 3.x
6.5
MEDIUM
Source:
NVD
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
CVSS 2.x
4 MEDIUM
AV:N/AC:L/Au:S/C:N/I:N/A:P
RedHat/V2
RedHat/V3
Ubuntu
LOW

An issue has been discovered in GitLab CE/EE affecting all versions starting from 12.10 before 14.3.6, all versions starting from 14.4 before 14.4.4, all versions starting from 14.5 before 14.5.2. A regular expression used for handling user input (notes, comments, etc) was susceptible to catastrophic backtracking that could cause a DOS attack.

Weakness

The product uses a regular expression with an inefficient, possibly exponential worst-case computational complexity that consumes excessive CPU cycles.

Affected Software

Name Vendor Start Version End Version
Gitlab Gitlab 12.10.0 (including) 14.3.6 (excluding)
Gitlab Gitlab 14.4.0 (including) 14.4.4 (excluding)
Gitlab Gitlab 14.5.0 (including) 14.5.2 (excluding)
Gitlab Ubuntu esm-apps/xenial *
Gitlab Ubuntu trusty *
Gitlab Ubuntu xenial *

Extended Description

	  Attackers can create crafted inputs that
	  intentionally cause the regular expression to use
	  excessive backtracking in a way that causes the CPU
	  consumption to spike.

Potential Mitigations

References