CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
Lifecycle Timeline
4Description
GitLab has remediated an issue in GitLab CE/EE affecting all versions from 17.7 before 18.8.7, 18.9 before 18.9.3, and 18.10 before 18.10.1 that could have allowed an authenticated user to execute arbitrary JavaScript in a user's browser due to improper sanitization of entity-encoded content in Mermaid diagrams.
Analysis
This vulnerability is a stored cross-site scripting (XSS) flaw in GitLab's Mermaid diagram rendering that allows authenticated users to inject arbitrary JavaScript code into other users' browsers through improperly sanitized entity-encoded content. The vulnerability affects GitLab CE/EE versions 17.7 before 18.8.7, 18.9 before 18.9.3, and 18.10 before 18.10.1, with a CVSS score of 5.4 (medium severity). …
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Remediation
Within 30 days: Identify affected systems running GitLab CE/EE affecting all and apply vendor patches as part of regular patch cycle. Verify Content-Security-Policy and output encoding.
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External POC / Exploit Code
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EUVD-2026-15809