GitLab CE/EE Unauth Org Join via Header Manipulation (pre18.6.1)
CVE-2025-12653 Published on November 26, 2025
Authentication Bypass by Spoofing in GitLab
GitLab has remediated an issue in GitLab CE/EE affecting all versions from 18.3 before 18.4.5, 18.5 before 18.5.3, and 18.6 before 18.6.1 that under specific conditions could have allowed an unauthenticated user to join arbitrary organizations by changing headers on some requests.
Vulnerability Analysis
CVE-2025-12653 can be exploited with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have a small impact on confidentiality and integrity, and no impact on availability.
Weakness Type
Authentication Bypass by Spoofing
This attack-focused weakness is caused by improperly implemented authentication schemes that are subject to spoofing attacks.
Products Associated with CVE-2025-12653
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Affected Versions
GitLab:- Version 18.3 and below 18.4.5 is affected.
- Version 18.5 and below 18.5.3 is affected.
- Version 18.6 and below 18.6.1 is affected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.