{
"id": "GHSA-m2w9-h2mm-79qr",
"aliases": [
"CVE-2026-6739"
],
"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 require system-level permission when patching protected default system roles, which allows authenticated users with delegated user-management permissions to escalate privileges by altering built-in role permissions via the role patch API. Mattermost Advisory ID: MMSA-2026-00656",
"summary": "Mattermost doesn't require system-level permission when patching protected default system roles",
"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": "8.0.0-20260501142004-99b73d4c4acf"
}
]
}
],
"package": {
"name": "github.com/mattermost/mattermost/server/v8",
"ecosystem": "Go"
}
}
],
"modified": "2026-08-24T21:43:02Z",
"severity": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:L"
}
],
"published": "2026-06-12T18:31:59Z",
"references": [
{
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-6739",
"type": "ADVISORY"
},
{
"url": "https://github.com/mattermost/mattermost/pull/36197",
"type": "WEB"
},
{
"url": "https://github.com/mattermost/mattermost/pull/36377",
"type": "WEB"
},
{
"url": "https://github.com/mattermost/mattermost/pull/36379",
"type": "WEB"
},
{
"url": "https://github.com/mattermost/mattermost/pull/36380",
"type": "WEB"
},
{
"url": "https://github.com/mattermost/mattermost/pull/36382",
"type": "WEB"
},
{
"url": "https://github.com/mattermost/mattermost/commit/2c89c2f6768fbe4dfd57a21ca38c0aecead8d4a8",
"type": "WEB"
},
{
"url": "https://github.com/mattermost/mattermost/commit/5e159647b16e571b327ac6882f32eae42971f540",
"type": "WEB"
},
{
"url": "https://github.com/mattermost/mattermost/commit/8000e5933526f4fd66b92131db3a1b1f4520dbae",
"type": "WEB"
},
{
"url": "https://github.com/mattermost/mattermost/commit/f0a390b96e4c730daedbaf5190684776730218c7",
"type": "WEB"
},
{
"url": "https://github.com/mattermost/mattermost",
"type": "PACKAGE"
},
{
"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"
}
],
"schema_version": "1.4.0",
"database_specific": {
"cwe_ids": [
"CWE-863"
],
"severity": "MODERATE",
"github_reviewed": true,
"nvd_published_at": "2026-06-12T17:16:27Z",
"github_reviewed_at": "2026-08-24T21:41:52Z"
}
}