CVE-2026-3254 PUBLISHED

Improper Restriction of Rendered UI Layers or Frames in GitLab

Assigner: GitLab
Reserved: 26.02.2026 Published: 22.04.2026 Updated: 22.04.2026

GitLab has remediated an issue in GitLab CE/EE affecting all versions from 18.11 before 18.11.1 that under certain conditions could have allowed an authenticated user to load unauthorized content into another user's browser due to improper input validation in the Mermaid sandbox.

Metrics

CVSS 3.1

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N
CVSS Score: 3.5

Attack Vector	Network	Scope	Unchanged
Attack Complexity	Low	Confidentiality Impact	None
Privileges Required	Low	Integrity Impact	Low
User Interaction	Required	Availability Impact	None

CVSS 3.1

Product Status

Vendor	GitLab
Product	GitLab
Versions	Default: unaffected affected from 18.11 to 18.11.1 (excl.)

Solutions

Upgrade to version 18.11.1 or above.

Credits

Thanks [joaxcar](https://hackerone.com/joaxcar) for reporting this vulnerability through our HackerOne bug bounty program finder

References

Problem Types

CWE-1021: Improper Restriction of Rendered UI Layers or Frames CWE