Vulnerabilities in pkg:golang/github.com/mattermost/mattermost-server

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-xmfh-3ccg-c9fx",
  "modified" : "2026-09-22T14:38:50Z",
  "published" : "2026-06-22T18:34:16Z",
  "aliases" : [ "CVE-2026-8823" ],
  "summary" : "Mattermost has an Incorrect Authorization issue",
  "details" : "Mattermost versions 11.7.x <= 11.7.0, 10.11.x <= 10.11.17 fail to validate bot targets when demoting users to guests which allows a lower-privileged administrator to degrade arbitrary bot accounts via the standard demote-user API.. Mattermost Advisory ID: MMSA-2026-00669",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:L/A:L"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/mattermost/mattermost-server"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "11.7.0"
      }, {
        "fixed" : "11.7.1"
      } ]
    } ],
    "versions" : [ "11.7.0" ]
  }, {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/mattermost/mattermost-server"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "10.11.0"
      }, {
        "fixed" : "10.11.18"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/mattermost/mattermost/server/v8"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "8.0.0-20260518160100-9bd77d3fc4d2"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-8823"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/mattermost/mattermost/pull/36487"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/mattermost/mattermost/commit/7972fc53f5c0b0175879a9737308a87b42db1f0b"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/mattermost/mattermost/commit/9bd77d3fc4d2af3f7f0259a205174e76a1a276e1"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/mattermost/mattermost/commit/c9bf3609fb9a3e5c2de94c50742c9b91fd723e3d"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/mattermost/mattermost/commit/d9a55e394cd5bc15edb49e9606bec8fec03ac4c6"
  }, {
    "type" : "WEB",
    "url" : "https://docs.mattermost.com/security-guide/security-updates"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/mattermost/mattermost"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/mattermost/mattermost/releases/tag/v10.11.18"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/mattermost/mattermost/releases/tag/v11.7.1"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-863" ],
    "severity" : "LOW",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-09-22T14:38:49Z",
    "nvd_published_at" : "2026-06-22T16:16:42Z"
  }
}