{"action":"Upgrade github.com/mattermost/mattermost-server to 10.11.13 or later.","affected":[{"fixed":"10.11.13","introduced":"10.11.0-rc1"},{"fixed":"11.5.0","introduced":"11.5.0-rc1"},{"fixed":"11.4.3","introduced":"11.4.0-rc1"},{"fixed":"11.3.3","introduced":"11.3.0-rc1"}],"component":"github.com/mattermost/mattermost-server","cve_ids":["CVE-2026-3590"],"ecosystem":"Go","epss":0.00152,"exploited":false,"fixed_versions":["10.11.13","11.5.0","11.4.3","11.3.3"],"ghsa_id":"GHSA-mh4x-rmrx-3hp4","id":"tcs_01M5KFFX1GPXY2RVARXYRGHF1N","modified_at":"2026-06-25T23:11:44.105865703Z","published_at":"2026-04-17T15:31:17Z","references":["https://osv.dev/vulnerability/GHSA-mh4x-rmrx-3hp4","https://nvd.nist.gov/vuln/detail/CVE-2026-3590","https://github.com/mattermost/mattermost","https://mattermost.com/security-updates"],"severity":{"label":"medium","score":6.5},"sources":[{"source":"osv","source_id":"GHSA-mh4x-rmrx-3hp4#Go/github.com/mattermost/mattermost-server","url":"https://osv.dev/vulnerability/GHSA-mh4x-rmrx-3hp4"}],"summary":"Mattermost has session spoofing due to lack of single-use consumption of guest magic link tokens enforcement"}