Vulnerability · Published Sep 29, 2026 · Assigned by GitLab
CVE-2026-84739Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') in GitLab
High 8.7
In plain English
A high-severity cross-site scripting in GitLab from GitLab. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 28% of all known vulnerabilities).
Severity (CVSS 3.1)8.7High
Exploit odds (30 days)0.3%top 72.1% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
GitLab has remediated an issue in GitLab CE/EE affecting all versions from 13.11 before 19.2.7, 19.3 before 19.3.3, and 19.4 before 19.4.1 that under certain conditions could have allowed an authenticated user to execute arbitrary JavaScript in the context of another user's browser session due to improper sanitization of path components in the merge request diff viewer.
Affected products (as reported)
Weakness: CWE-79 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N
References
- https://gitlab.com/gitlab-org/gitlab/-/work_items/627316
- HackerOne Bug Bounty Report #3938482 technical-description, exploit, permissions-required
- https://docs.gitlab.com/releases/patches/patch-release-gitlab-19-4-1-released/