{"id":"CVE-2017-18897","aliases":["GHSA-f7c3-7vp3-44p6","GO-2026-4301"],"url":"https://o3.security/vulnerability/CVE-2017-18897","summary":"Mattermost Server mishandles redirect denial action","details":"An issue was discovered in Mattermost Server before 4.2.0, 4.1.1, and 4.0.5, when used as an OAuth 2.0 service provider. It mishandles a deny action for a redirection.","published":"2020-06-19T19:15:11.327Z","modified":"2026-08-27T08:19:01.167280Z","cvss":{"score":6.1,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N"},"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"Go","name":"github.com/mattermost/mattermost-server","fixedVersion":"4.0.5"},{"ecosystem":"Go","name":"github.com/mattermost/mattermost-server","fixedVersion":"4.1.1"},{"ecosystem":"Go","name":"github.com/mattermost/mattermost-server","fixedVersion":"4.2.0"}],"fix":null,"references":[{"type":"ADVISORY","url":"https://mattermost.com/security-updates/"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-27T08:19:01.167280Z"}}