{
"id": "GHSA-3vmp-whvv-5v9v",
"aliases": [
"CVE-2026-6046"
],
"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",
"summary": "Mattermost doesn't validate that a username returned during bot registration belongs to a bot account",
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "11.6.0"
},
{
"fixed": "11.6.1"
}
]
}
],
"package": {
"name": "github.com/mattermost/mattermost-server",
"ecosystem": "Go"
},
"versions": [
"11.6.0"
]
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "11.5.0"
},
{
"fixed": "11.5.5"
}
]
}
],
"package": {
"name": "github.com/mattermost/mattermost-server",
"ecosystem": "Go"
},
"database_specific": {
"last_known_affected_version_range": "<= 11.5.4"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "10.11.0"
},
{
"fixed": "10.11.17"
}
]
}
],
"package": {
"name": "github.com/mattermost/mattermost-server",
"ecosystem": "Go"
},
"database_specific": {
"last_known_affected_version_range": "<= 10.11.15"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "8.0.0-20250731163400-5b955468ea1e"
},
{
"fixed": "8.0.0-20260428151657-c79c3831061a"
}
]
}
],
"package": {
"name": "github.com/mattermost/mattermost/server/v8",
"ecosystem": "Go"
}
}
],
"modified": "2026-08-24T21:39:54Z",
"severity": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N"
}
],
"published": "2026-06-12T18:31:59Z",
"references": [
{
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-6046",
"type": "ADVISORY"
},
{
"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": "WEB"
},
{
"url": "https://github.com/mattermost/mattermost",
"type": "PACKAGE"
}
],
"schema_version": "1.4.0",
"database_specific": {
"cwe_ids": [
"CWE-200"
],
"severity": "MODERATE",
"github_reviewed": true,
"nvd_published_at": "2026-06-12T17:16:26Z",
"github_reviewed_at": "2026-08-24T21:39:13Z"
}
}