{"action":"Upgrade github.com/mattermost/mattermost/server/v8 to 8.0.0-20260401090745-f4d1abe7e8f5 or later.","affected":[{"fixed":"11.5.2","introduced":"11.5.0"},{"fixed":"8.0.0-20260401090745-f4d1abe7e8f5","introduced":"0"}],"component":"github.com/mattermost/mattermost/server/v8","cve_ids":["CVE-2026-5163"],"ecosystem":"Go","epss":0.00205,"exploited":false,"fixed_versions":["11.5.2","8.0.0-20260401090745-f4d1abe7e8f5"],"ghsa_id":"GHSA-8r89-8w26-cq32","id":"tcs_01M5KF4982SYRPXNDP5YMN3A94","modified_at":"2026-06-25T19:56:31.484534506Z","published_at":"2026-05-18T09:31:48Z","references":["https://osv.dev/vulnerability/GHSA-8r89-8w26-cq32","https://nvd.nist.gov/vuln/detail/CVE-2026-5163","https://github.com/mattermost/mattermost/commit/f4d1abe7e8f545f1a87f463fa9fe451c731aebf8","https://github.com/mattermost/mattermost","https://mattermost.com/security-updates"],"severity":{"label":"medium","score":6.5},"sources":[{"source":"osv","source_id":"GHSA-8r89-8w26-cq32","url":"https://osv.dev/vulnerability/GHSA-8r89-8w26-cq32"}],"summary":"Mattermost doesn't verify channel membership when processing AI-assisted message rewrites"}