{"id":"CVE-2026-6046","aliases":["GHSA-3vmp-whvv-5v9v"],"url":"https://o3.security/vulnerability/CVE-2026-6046","summary":"Plugin bot username conflict allows user account to be used as bot identity in Mattermost Server","details":"Mattermost versions 11.6.x <= 11.6.1, 11.5.x <= 11.5.4, 10.11.x <= 10.11.15, 10.11.x <= 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","published":"2026-06-12T15:52:33.505Z","modified":"2026-09-29T18:26:50.911546827Z","cvss":{"score":5.3,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N"},"epss":{"score":0.0019,"percentile":0.08712,"asOf":"2026-09-01"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"Go","name":"github.com/mattermost/mattermost-server","fixedVersion":"11.6.1"},{"ecosystem":"Go","name":"github.com/mattermost/mattermost-server","fixedVersion":"11.5.5"},{"ecosystem":"Go","name":"github.com/mattermost/mattermost-server","fixedVersion":"10.11.17"},{"ecosystem":"Go","name":"github.com/mattermost/mattermost/server/v8","fixedVersion":"8.0.0-20260428151657-c79c3831061a"}],"fix":{"url":"https://github.com/mattermost/mattermost/pull/36320","label":"mattermost/mattermost#36320"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/6xxx/CVE-2026-6046.json"},{"type":"ADVISORY","url":"https://mattermost.com/security-updates"},{"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":"PACKAGE","url":"https://github.com/mattermost/mattermost"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-09-29T18:26:50.911546827Z"}}