Improper Restriction of Rendered UI Layers or Frames in Gitlab Community Edition and GitLab Enterprise Edition - CVE-2026-3254
Published: May 18, 2026
Vulnerability identifier: #VU131661
CSH Severity: Low
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Clear
CVE-ID: CVE-2026-3254
CWE-ID: CWE-1021
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: GitLab, Inc
Affected software:
Gitlab Community Edition
GitLab Enterprise Edition
Gitlab Community Edition
GitLab Enterprise Edition
Detailed vulnerability description
The vulnerability allows a remote user to load unauthorized content into another user's browser.
The vulnerability exists due to improper restriction of rendered ui layers or frames in Mermaid sandbox when rendering Mermaid content under certain conditions. A remote user can supply crafted input to load unauthorized content into another user's browser.
User interaction is required.
How to mitigate CVE-2026-3254
Install security update from vendor's website.