CVE-2025-27715: Mattermost fail to prompt for explicit approval before adding a team admin to a private channel

March 21, 2025

Mattermost versions 9.11.x <= 9.11.8 fail to prompt for explicit approval before adding a team admin to a private channel, which team admins to joining private channels via crafted permalink links without explicit consent from them.

References

github.com/advisories/GHSA-cw7q-5cgc-h3h9
github.com/mattermost/mattermost
mattermost.com/security-updates
nvd.nist.gov/vuln/detail/CVE-2025-27715

Code Behaviors & Features

Detect and mitigate CVE-2025-27715 with GitLab Dependency Scanning

Secure your software supply chain by verifying that all open source dependencies used in your projects contain no disclosed vulnerabilities. Learn more about Dependency Scanning →