GitLab CE/EE Merge Request Title Leak (18.4.6, 18.5.4, 18.6.2)
CVE-2025-12734 Published on December 11, 2025
Improper Encoding or Escaping of Output in GitLab
GitLab has remediated an issue in GitLab CE/EE affecting all versions from 15.6 before 18.4.6, 18.5 before 18.5.4, and 18.6 before 18.6.2 that could have allowed an authenticated user to, under certain conditions, render content in dialogs to other users by injecting malicious HTML content into merge request titles.
Vulnerability Analysis
CVE-2025-12734 is exploitable with network access, requires user interaction and a small amount of user privileges. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality, with no impact on integrity, and no impact on availability.
Weakness Type
What is an Output Sanitization Vulnerability?
The software prepares a structured message for communication with another component, but encoding or escaping of the data is either missing or done incorrectly. As a result, the intended structure of the message is not preserved.
CVE-2025-12734 has been classified to as an Output Sanitization vulnerability or weakness.
Products Associated with CVE-2025-12734
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Affected Versions
GitLab:- Version 15.6 and below 18.4.6 is affected.
- Version 18.5 and below 18.5.4 is affected.
- Version 18.6 and below 18.6.2 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.