CVE-2026-0752: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') in GitLab

Severity: medium (CVSS 6.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-02-25 · updated 2026-06-17
Weakness: CWE-79

Description

GitLab has remediated an issue in GitLab CE/EE affecting all versions from 16.2 before 18.7.5, 18.8 before 18.8.5, and 18.9 before 18.9.1 that under certain circumstances, could have allowed an unauthenticated user to inject arbitrary scripts into the Mermaid sandbox UI.

Affected products

GitLab: from 16.2.0 before 18.7.5; from 18.8.0 before 18.8.5; 18.9.0 — fixed in 18.7.5, 18.8.5

How to fix

Upgrade to a fixed version: GitLab 18.7.5, 18.8.5. Check the vendor advisory for mitigations.

References

https://about.gitlab.com/releases/2026/02/25/patch-release-gitlab-18-9-1-released/
https://gitlab.com/gitlab-org/gitlab/-/issues/585371
https://hackerone.com/reports/3473276

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