{"action":"No fix published. Pin and monitor.","affected":[{"introduced":"0"}],"component":"github.com/mattermost/mattermost-server/v5","cve_ids":["CVE-2026-5740"],"ecosystem":"Go","epss":0.0034,"exploited":false,"fixed_versions":[],"ghsa_id":"GHSA-w9m8-p4cc-4qj9","id":"tcs_01M5KGQ67BNNB9S17XF297AGRF","modified_at":"2026-07-07T16:01:34.665634742Z","published_at":"2026-07-07T15:26:32Z","references":["https://osv.dev/vulnerability/GO-2026-5838","https://github.com/advisories/GHSA-w9m8-p4cc-4qj9","https://nvd.nist.gov/vuln/detail/CVE-2026-5740","https://github.com/mattermost/mattermost/commit/17939826efa20a97f087b3d390ec5136df350bae","https://mattermost.com/security-updates"],"severity":{"label":"unknown"},"sources":[{"source":"osv","source_id":"GO-2026-5838#Go/github.com/mattermost/mattermost-server/v5","url":"https://osv.dev/vulnerability/GO-2026-5838"}],"summary":"Mattermost doesn't properly validate msgpack-encoded WebSocket frames before memory allocation in github.com/mattermost/mattermost-server"}