{"action":"Upgrade github.com/mattermost/mattermost/server/v8 to 8.0.0-20260217110922-b7d4a1f1f59b or later.","affected":[{"fixed":"8.0.0-20260217110922-b7d4a1f1f59b","introduced":"8.0.0-20260105080200-d27a2195068d"}],"component":"github.com/mattermost/mattermost/server/v8","cve_ids":["CVE-2026-27656"],"ecosystem":"Go","epss":0.00183,"exploited":false,"fixed_versions":["8.0.0-20260217110922-b7d4a1f1f59b"],"ghsa_id":"GHSA-fg35-5rf6-qg3g","id":"tcs_01M5KF946P69XTYFW7XPVKSXGB","modified_at":"2026-06-25T19:56:08.822530656Z","published_at":"2026-03-25T18:31:53Z","references":["https://osv.dev/vulnerability/GHSA-fg35-5rf6-qg3g","https://nvd.nist.gov/vuln/detail/CVE-2026-27656","https://github.com/mattermost/mattermost","https://mattermost.com/security-updates"],"severity":{"label":"medium","score":5.7},"sources":[{"source":"osv","source_id":"GHSA-fg35-5rf6-qg3g#Go/github.com/mattermost/mattermost/server/v8","url":"https://osv.dev/vulnerability/GHSA-fg35-5rf6-qg3g"}],"summary":"Mattermost allows attackers to take over arbitrary user accounts via overly permissive substring matching flaw"}