{"id":"CVE-2017-18894","aliases":["GHSA-gg42-mwr6-p82c","GO-2026-4297"],"url":"https://o3.security/vulnerability/CVE-2017-18894","summary":"Mattermost Server has intermittent Authorization bypass for resource-owners","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. Resource-owner authorization can be intermittently bypassed, allowing account takeover.","published":"2020-06-19T19:15:10.967Z","modified":"2026-08-27T08:18:56.546698Z","cvss":{"score":8.1,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/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/"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2017-18894"},{"type":"PACKAGE","url":"https://github.com/mattermost/mattermost"},{"type":"WEB","url":"https://mattermost.com/security-updates"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-27T08:18:56.546698Z"}}