{"action":"Upgrade github.com/mattermost/mattermost-server to 10.11.13+incompatible or later.","affected":[{"fixed":"10.11.13+incompatible","introduced":"10.11.0-rc1+incompatible"},{"fixed":"11.3.3+incompatible","introduced":"11.3.0-rc1+incompatible"},{"fixed":"11.4.3+incompatible","introduced":"11.4.0-rc1+incompatible"},{"fixed":"11.5.0+incompatible","introduced":"11.5.0-rc1+incompatible"}],"component":"github.com/mattermost/mattermost-server","cve_ids":["CVE-2026-3590"],"ecosystem":"Go","epss":0.00152,"exploited":false,"fixed_versions":["10.11.13+incompatible","11.3.3+incompatible","11.4.3+incompatible","11.5.0+incompatible"],"ghsa_id":"GHSA-mh4x-rmrx-3hp4","id":"tcs_01M5KGMVGW8HFQNYZWV3MDP90A","modified_at":"2026-06-25T23:01:02.100908217Z","published_at":"2026-06-25T22:34:31Z","references":["https://osv.dev/vulnerability/GO-2026-5507","https://github.com/advisories/GHSA-mh4x-rmrx-3hp4","https://nvd.nist.gov/vuln/detail/CVE-2026-3590","https://mattermost.com/security-updates"],"severity":{"label":"medium","score":6.5},"sources":[{"source":"osv","source_id":"GO-2026-5507","url":"https://osv.dev/vulnerability/GO-2026-5507"},{"source":"nvd","source_id":"CVE-2026-3590","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-3590"}],"summary":"Mattermost has session spoofing due to lack of single-use consumption of guest magic link tokens enforcement in github.com/mattermost/mattermost-server"}