{"action":"No fix published. Pin and monitor.","affected":[{"introduced":"0"}],"component":"github.com/mattermost/mattermost-server/v5","cve_ids":["CVE-2026-27656"],"ecosystem":"Go","epss":0.00324,"exploited":false,"fixed_versions":[],"ghsa_id":"GHSA-fg35-5rf6-qg3g","id":"tcs_01M5KGKS4H7FSPYCKFWS0SF1MR","modified_at":"2026-06-25T19:45:34.725735565Z","published_at":"2026-06-25T18:43:19Z","references":["https://osv.dev/vulnerability/GO-2026-5360","https://github.com/advisories/GHSA-fg35-5rf6-qg3g","https://nvd.nist.gov/vuln/detail/CVE-2026-27656","https://mattermost.com/security-updates"],"severity":{"label":"unknown"},"sources":[{"source":"osv","source_id":"GO-2026-5360#Go/github.com/mattermost/mattermost-server/v5","url":"https://osv.dev/vulnerability/GO-2026-5360"}],"summary":"Mattermost allows attackers to take over arbitrary user accounts via overly permissive substring matching flaw in github.com/mattermost/mattermost-server"}