CVE-2025-6226: Mattermost Missing Authentication for Critical Function

July 18, 2025 (updated July 21, 2025)

Mattermost versions 10.5.x <= 10.5.6, 10.8.x <= 10.8.1, 10.7.x <= 10.7.3, 9.11.x <= 9.11.16 fail to verify authorization when retrieving cached posts by PendingPostID which allows an authenticated user to read posts in private channels they don’t have access to via guessing the PendingPostID of recently created posts.

References

github.com/advisories/GHSA-7h34-9chr-58qh
github.com/mattermost/mattermost
github.com/mattermost/mattermost/commit/fa40a8c5d47fed5c166429a1c1bd95d62b241d89
mattermost.com/security-updates
nvd.nist.gov/vuln/detail/CVE-2025-6226

Code Behaviors & Features

Detect and mitigate CVE-2025-6226 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 →