CVE-2026-3117 Instance and webhook GitLab plugin commands were able to be run by non-admin users
Non-admin users can execute privileged GitLab plugin commands to uninstall instances or configure webhooks due to missing permission checks.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-3117?
CVE-2026-3117 is a medium-severity missing authorization vulnerability in Mattermost Mattermost Server, published on 18 May 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
Mattermost Plugins versions <=11.5 11.1.5 10.13.11 11.3.4.0 fail to properly check for permissions when processing commands in the Gitlab plugin which allows normal users to uninstall instances or setup webhook connections via the {{gitlab instance {option}}} or the {{/gitlab webhook {option}}} commands. Mattermost Advisory ID: MMSA-2026-00600
Weakness: CWE-862
Which versions are affected by CVE-2026-3117?
It affects 1 product.
Products include Mattermost Mattermost Server.
How do I fix CVE-2026-3117?
No fix has been published for CVE-2026-3117 yet. Limit exposure of the affected software until one is available.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-3117 being exploited?
There is no known exploitation of CVE-2026-3117 in the wild and no public exploit code.
Other vulnerabilities in Mattermost Mattermost Server
- CVE-2025-12419 Account takeover on OAuth/OpenID-enabled servers
- CVE-2025-12421 Account Takeover via Code Exchange Endpoint
- CVE-2025-4981 Path Traversal Leading to RCE by Any Authenticated Mattermost User
- CVE-2025-20051 Arbitrary file read via block duplication in Mattermost Boards
- CVE-2025-25279 Arbitrary file read in Mattermost Boards via import & export board archive
Sources
Also known as GHSA-5gjv-5xhr-vc35.