Description
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.
Affected products
gitlab: gitlab
References2
- gitlab.com/gitlab-org/gitlab/-/work_items/591587 Broken Link
- hackerone.com/reports/3572752 Permissions Required
Metrics
- CVSS 3.1
-
3.5
LOW
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N - EPSS — exploit probability
- 0% percentile: 4 · as of 13 November 2026
- CWE
- CWE-1021
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.