{"id":"CVE-2017-18889","aliases":["GHSA-jp57-4x34-5v94","GO-2025-4201"],"url":"https://o3.security/vulnerability/CVE-2017-18889","summary":"Mattermost Server is vulnerable to webhook and slash command manipulation","details":"An issue was discovered in Mattermost Server before 4.3.0, 4.2.1, and 4.1.2. An attacker could create fictive system-message posts via webhooks and slash commands, in the v3 or v4 REST API.","published":"2020-06-19T19:15:10.653Z","modified":"2026-08-27T08:18:58.001931Z","cvss":{"score":4.3,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N"},"epss":null,"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":"2026-08-27T08:18:58.001931Z"}}