GitLab CE/EE XSS in MR Diff Viewer (v19.4.1)
CVE-2026-84739 Published on September 29, 2026
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') in GitLab
GitLab has remediated an issue in GitLab CE/EE affecting all versions from 13.11 before 19.2.7, 19.3 before 19.3.3, and 19.4 before 19.4.1 that under certain conditions could have allowed an authenticated user to execute arbitrary JavaScript in the context of another user's browser session due to improper sanitization of path components in the merge request diff viewer.
Vulnerability Analysis
CVE-2026-84739 can be exploited 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 a high impact on confidentiality and integrity, and no impact on availability.
Weakness Type
What is a XSS Vulnerability?
The software does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.
CVE-2026-84739 has been classified to as a XSS vulnerability or weakness.
Products Associated with CVE-2026-84739
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Affected Versions
GitLab:- Version 13.11 and below 19.2.7 is affected.
- Version 19.3 and below 19.3.3 is affected.
- Version 19.4 and below 19.4.1 is affected.