# CVE-2026-84739: GitLab cross-site scripting in merge request diff viewer

Source: https://junglewise.ai/threats/cve-2026-84739-gitlab-has-remediated-an-issue-in-gitlab-ce-ee-affecting-all  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-29. Updated: 2026-09-29  
License: CC BY 4.0 with a link back

CVE-2026-84739 · Severity: high · CVSS 8.7 · Published 2026-09-29

GitLab Community and Enterprise editions are vulnerable to stored cross-site scripting (XSS) in the merge request diff viewer that allows an authenticated attacker to inject malicious JavaScript into another user's browser session. This could enable account takeover, credential theft, or other attacks against other GitLab users viewing merge requests with specially crafted file paths.

Technologies: [GitLab Community Edition](https://junglewise.ai/threats/technologies/gitlab-ce), [GitLab Enterprise Edition](https://junglewise.ai/threats/technologies/gitlab-ee). Vendors: [GitLab](https://junglewise.ai/threats/vendors/gitlab).

## Quick answers

**Is CVE-2026-84739 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-84739 being exploited in the wild.

**How severe is CVE-2026-84739?** High severity, with a CVSS score of 8.7, published 29 September 2026.

**Which products and versions are affected?** GitLab Community Edition 13.11 before 19.2.7, 19.3 before 19.3.3, 19.4 before 19.4.1; GitLab Enterprise Edition 13.11 before 19.2.7, 19.3 before 19.3.3, 19.4 before 19.4.1.

**Is there a fix for CVE-2026-84739?** A patch was published on 2026-09-23: Patched in versions 19.2.7, 19.3.3, 19.4.1 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-84739 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-84739?** Check whether you run GitLab Community Edition or GitLab Enterprise Edition at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The vulnerability exists in the merge request diff viewer component due to improper sanitization of path components, allowing an authenticated attacker to inject arbitrary JavaScript that executes in the context of another user's browser. The attack requires user interaction (a victim must view the malicious merge request diff) and authentication to create the malicious merge request. Patched versions: 19.2.7, 19.3.3, 19.4.1.

## Affected products

- GitLab Community Edition 13.11 before 19.2.7, 19.3 before 19.3.3, 19.4 before 19.4.1
- GitLab Enterprise Edition 13.11 before 19.2.7, 19.3 before 19.3.3, 19.4 before 19.4.1

## Timeline

- 2026-09-29: disclosed: CVE-2026-84739 published
- 2026-09-23: patched: Patched in versions 19.2.7, 19.3.3, 19.4.1

## References

- [https://docs.gitlab.com/releases/patches/patch-release-gitlab-19-4-1-released/](https://docs.gitlab.com/releases/patches/patch-release-gitlab-19-4-1-released/)
- [https://gitlab.com/gitlab-org/gitlab/-/work_items/627316](https://gitlab.com/gitlab-org/gitlab/-/work_items/627316)

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- [GitLab Enterprise Edition authorization bypass in billing validation](https://junglewise.ai/threats/cve-2026-112378-gitlab-has-remediated-an-issue-in-gitlab-ee-affecting-all)
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