CVE-2025-14350: Mattermost fails to properly validate team membership when processing channel mentions

February 16, 2026 (updated February 19, 2026)

Mattermost versions 11.1.x <= 11.1.2, 10.11.x <= 10.11.9, 11.2.x <= 11.2.1 fail to properly validate team membership when processing channel mentions which allows authenticated users to determine the existence of teams and their URL names via posting channel shortlinks and observing the channel_mentions property in the API response. Mattermost Advisory ID: MMSA-2025-00563

References

github.com/advisories/GHSA-57cc-2pf4-mhmx
github.com/mattermost/mattermost
github.com/mattermost/mattermost/commit/761e56bb11ccb751ddbe4bab5898ccc2b384fd82
mattermost.com/security-updates
nvd.nist.gov/vuln/detail/CVE-2025-14350

Code Behaviors & Features

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