{"action":"Upgrade github.com/mattermost/mattermost-server to 5.3.2-0.20260325160634-e738016c5920 or later.","affected":[{"fixed":"5.3.2-0.20260325160634-e738016c5920","introduced":"0"}],"component":"github.com/mattermost/mattermost-server","cve_ids":["CVE-2026-6333"],"ecosystem":"Go","epss":0.00137,"exploited":false,"fixed_versions":["5.3.2-0.20260325160634-e738016c5920"],"ghsa_id":"GHSA-vqp5-2mrp-qqxg","id":"tcs_01M5KFPHFZTQ5SYS0ZZYRFDAFV","modified_at":"2026-06-25T23:11:07.798838866Z","published_at":"2026-05-18T09:31:48Z","references":["https://osv.dev/vulnerability/GHSA-vqp5-2mrp-qqxg","https://nvd.nist.gov/vuln/detail/CVE-2026-6333","https://github.com/mattermost/mattermost/commit/e738016c592045e14bf926eafaeda6f8521def6d","https://github.com/mattermost/mattermost","https://mattermost.com/security-updates"],"severity":{"label":"low","score":3.5},"sources":[{"source":"osv","source_id":"GHSA-vqp5-2mrp-qqxg#Go/github.com/mattermost/mattermost-server","url":"https://osv.dev/vulnerability/GHSA-vqp5-2mrp-qqxg"}],"summary":"Mattermost doesn't validate the Host header when constructing response URLs for custom slash command"}