CVE-2026-84739 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') in GitLab

High 8.7 Published 29 Sep 2026 Updated 29 Sep 2026

An authenticated user can execute arbitrary JavaScript in another user's browser via unsanitized path components in the merge request diff viewer.

Exploited in the wild: Not known
Login needed: Any signed-in user
Attackable: Over the internet
Victim action needed: A user has to click or open something
Fix: Available

What is CVE-2026-84739?

CVE-2026-84739 is a high-severity cross-site scripting vulnerability in Gitlab Gitlab, published on 29 Sep 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

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.

Weakness: CWE-79

Which versions are affected by CVE-2026-84739?

1 open source package ship an affected version, including gitlab. It affects 1 product.

Package	Affected	Fixed in
`gitlab` Bitnami	From `13.11.0`	`19.2.7, 19.3.3, 19.4.1`

Products include Gitlab Gitlab.

How do I fix CVE-2026-84739?

Upgrade gitlab to a fixed version for your release line: 19.2.7, 19.3.3 or 19.4.1.

Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.

Is CVE-2026-84739 being exploited?

There is no known exploitation of CVE-2026-84739 in the wild and no public exploit code.

All Gitlab Gitlab vulnerabilities

Sources

Also known as BIT-gitlab-2026-84739, GHSA-hrj5-qwx9-f2q7, MINI-4g8c-fr9q-jc96, MINI-hhh8-m975-2g5c, MINI-qjvv-8x9q-g6hh.