{"id":"CVE-2017-18877","aliases":["GHSA-9x8x-w6g5-hx4w","GO-2025-4190"],"url":"https://o3.security/vulnerability/CVE-2017-18877","summary":"Mattermost Server is vulnerable to XSS attacks against an OAuth 2.0 allow/deny page","details":"An issue was discovered in Mattermost Server before 4.3.0, 4.2.1, and 4.1.2. XSS attacks could occur against an OAuth 2.0 allow/deny page.","published":"2020-06-19T17:15:12.257Z","modified":"2026-08-27T08:18:54.202934Z","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":{"score":0.00685,"percentile":0.4954,"asOf":"2026-08-23"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"Go","name":"github.com/mattermost/mattermost-server","fixedVersion":"4.1.2"},{"ecosystem":"Go","name":"github.com/mattermost/mattermost-server","fixedVersion":"4.2.1"},{"ecosystem":"Go","name":"github.com/mattermost/mattermost-server","fixedVersion":"4.3.0"}],"fix":null,"references":[{"type":"ADVISORY","url":"https://mattermost.com/security-updates/"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-27T08:18:54.202934Z"}}