CVE-2023-3909 - CVE House
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Status published Medium CVE-2023-3909

Inefficient Regular Expression Complexity in GitLab

Vulnerability Description

An issue has been discovered in GitLab CE/EE affecting all versions starting from 12.3 before 16.3.6, all versions starting from 16.4 before 16.4.2, all versions starting from 16.5 before 16.5.1. A Regular Expression Denial of Service was possible by adding a large string in timeout input in gitlab-ci.yml file.

Impact Analysis

Refer to official advisory for detailed impact metrics.

Remediation

Ensure systems are updated to the latest vendor-supplied patch levels.

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Credits & Attribution

The following person or organization is credited with identifying this vulnerability, as recorded in the NVD database:

  • Thanks [akadrian](https://hackerone.com/akadrian) for reporting this vulnerability through our HackerOne bug bounty program

References

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CVE-2025-9642
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Affected Vendor

Affected Software

GitLab
Vulnerable Versions:
12.3, 16.4, 16.5

Timeline

Official Publish: November 6th, 2023
Last Modified: November 20th, 2025
Added to House: July 22nd, 2026

CVSS Vectors

V3: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L

Weaknesses (CWE)

CWE-1333

MITRE ATT&CK TTPs

T1499 Endpoint Denial of Service
Impact
T1190 Exploit Public-Facing Application
Initial Access
T1496 Resource Hijacking
Impact
T1562 Impair Defenses
Defense Evasion
T1070 Indicator Removal on Host
Defense Evasion