{"id":"GHSA-3vmp-whvv-5v9v","summary":"Mattermost doesn't validate that a username returned during bot registration belongs to a bot account","details":"Mattermost versions 11.6.x \u003c= 11.6.1, 11.5.x \u003c= 11.5.4, 10.11.x \u003c= 10.11.15, 10.11.x \u003c= 10.11.16 fail to validate that a username returned during bot registration belongs to a bot account, which allows an unprivileged attacker to intercept private messages sent by plugins via direct message channels by pre-registering a user account with a predictable plugin bot username. Mattermost Advisory ID: MMSA-2026-00649","aliases":["CVE-2026-6046","GO-2026-6279"],"modified":"2026-08-25T20:25:37.848525378Z","published":"2026-06-12T18:31:59Z","database_specific":{"github_reviewed":true,"github_reviewed_at":"2026-08-24T21:39:13Z","nvd_published_at":"2026-06-12T17:16:26Z","cwe_ids":["CWE-200"],"severity":"MODERATE"},"references":[{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-6046"},{"type":"WEB","url":"https://github.com/mattermost/mattermost/pull/36320"},{"type":"WEB","url":"https://github.com/mattermost/mattermost/pull/36318"},{"type":"WEB","url":"https://github.com/mattermost/mattermost/pull/36317"},{"type":"WEB","url":"https://github.com/mattermost/mattermost/pull/36305"},{"type":"WEB","url":"https://github.com/mattermost/mattermost/pull/36064"},{"type":"WEB","url":"https://github.com/mattermost/mattermost/commit/f706d1f01e6dfe62cab86c1d257f237daa78106a"},{"type":"WEB","url":"https://github.com/mattermost/mattermost/commit/c79c3831061a0880c0962c7d567c9e24dd35f44c"},{"type":"WEB","url":"https://github.com/mattermost/mattermost/commit/aba9339a24d4b287edd77377c19901d6e341bb96"},{"type":"WEB","url":"https://github.com/mattermost/mattermost/commit/98f9778cec1e7f3d97b3d4692fb91f8e7b659972"},{"type":"WEB","url":"https://github.com/mattermost/mattermost/commit/3be10297c14d272f273d747af70728f9d03c60ec"},{"type":"WEB","url":"https://github.com/mattermost/mattermost/releases/tag/v10.11.16"},{"type":"WEB","url":"https://github.com/mattermost/mattermost/releases/tag/v11.5.5"},{"type":"WEB","url":"https://github.com/mattermost/mattermost/releases/tag/v11.6.2"},{"type":"WEB","url":"https://github.com/mattermost/mattermost/releases/tag/v11.7.0"},{"type":"WEB","url":"https://mattermost.com/security-updates"},{"type":"PACKAGE","url":"https://github.com/mattermost/mattermost"}],"affected":[{"package":{"name":"github.com/mattermost/mattermost-server","ecosystem":"Go","purl":"pkg:golang/github.com/mattermost/mattermost-server"},"ranges":[{"type":"SEMVER","events":[{"introduced":"11.6.0"},{"fixed":"11.6.1"}]}],"versions":["11.6.0"],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/06/GHSA-3vmp-whvv-5v9v/GHSA-3vmp-whvv-5v9v.json"}},{"package":{"name":"github.com/mattermost/mattermost-server","ecosystem":"Go","purl":"pkg:golang/github.com/mattermost/mattermost-server"},"ranges":[{"type":"SEMVER","events":[{"introduced":"11.5.0"},{"fixed":"11.5.5"}]}],"database_specific":{"last_known_affected_version_range":"\u003c= 11.5.4","source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/06/GHSA-3vmp-whvv-5v9v/GHSA-3vmp-whvv-5v9v.json"}},{"package":{"name":"github.com/mattermost/mattermost-server","ecosystem":"Go","purl":"pkg:golang/github.com/mattermost/mattermost-server"},"ranges":[{"type":"SEMVER","events":[{"introduced":"10.11.0"},{"fixed":"10.11.17"}]}],"database_specific":{"last_known_affected_version_range":"\u003c= 10.11.15","source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/06/GHSA-3vmp-whvv-5v9v/GHSA-3vmp-whvv-5v9v.json"}},{"package":{"name":"github.com/mattermost/mattermost/server/v8","ecosystem":"Go","purl":"pkg:golang/github.com/mattermost/mattermost/server/v8"},"ranges":[{"type":"SEMVER","events":[{"introduced":"8.0.0-20250731163400-5b955468ea1e"},{"fixed":"8.0.0-20260428151657-c79c3831061a"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/06/GHSA-3vmp-whvv-5v9v/GHSA-3vmp-whvv-5v9v.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N"}]}