{"action":"Upgrade github.com/mattermost/mattermost-server to 5.3.2-0.20251210191531-cd17b61de41b or later.","affected":[{"introduced":"11.1.0"},{"introduced":"10.11.0"},{"introduced":"11.2.0"},{"fixed":"5.3.2-0.20251210191531-cd17b61de41b","introduced":"0"}],"component":"github.com/mattermost/mattermost-server","cve_ids":["CVE-2025-13821"],"ecosystem":"Go","epss":0.00238,"exploited":false,"fixed_versions":["5.3.2-0.20251210191531-cd17b61de41b"],"ghsa_id":"GHSA-pp9j-pf5c-659x","id":"tcs_01M5KFHMH249J19EVCR7GCK294","modified_at":"2026-04-01T17:35:09.396122Z","published_at":"2026-02-16T12:30:25Z","references":["https://osv.dev/vulnerability/GHSA-pp9j-pf5c-659x","https://nvd.nist.gov/vuln/detail/CVE-2025-13821","https://github.com/mattermost/mattermost/commit/cd17b61de41bf0a49b524bb91ce0bbe859e5a100","https://github.com/mattermost/mattermost","https://mattermost.com/security-updates"],"severity":{"label":"medium","score":5.7},"sources":[{"source":"osv","source_id":"GHSA-pp9j-pf5c-659x#Go/github.com/mattermost/mattermost-server","url":"https://osv.dev/vulnerability/GHSA-pp9j-pf5c-659x"}],"summary":"Mattermost fails to sanitize sensitive data in WebSocket messages"}