{
  "schemaVersion": 1,
  "attribution": [
    {
      "source": "CISA Known Exploited Vulnerabilities",
      "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog",
      "licence": "US government work"
    },
    {
      "source": "GitHub Advisory Database",
      "url": "https://github.com/advisories",
      "licence": "CC BY 4.0"
    },
    {
      "source": "Have I Been Pwned",
      "url": "https://haveibeenpwned.com/",
      "licence": "CC BY 4.0"
    },
    {
      "source": "CVE Program (CVE records)",
      "url": "https://www.cve.org/Legal/TermsOfUse",
      "licence": "CVE Terms of Use",
      "notice": "Copyright © 1999-2026, The MITRE Corporation. CVE is a trademark and the CVE logo is a registered trademark of The MITRE Corporation.",
      "terms": "CVE Usage: MITRE hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute Common Vulnerabilities and Exposures (CVE™). Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy."
    },
    {
      "source": "FIRST EPSS",
      "url": "https://www.first.org/epss/",
      "licence": "free to use; FIRST requests attribution"
    }
  ],
  "record": {
    "id": "CVE-2026-28759",
    "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2026-28759",
    "idYear": 2026,
    "status": "PUBLISHED",
    "publishedAt": "2026-05-18T06:50:07.346Z",
    "updatedAt": "2026-05-18T14:36:08.107Z",
    "importedAt": "2026-10-24T01:58:02.025Z",
    "snapshot": {
      "id": "cve_2026-10-24_midnight_baseline",
      "at": "2026-10-24T00:00:00.000Z",
      "source": "https://github.com/CVEProject/cvelistV5/releases/tag/cve_2026-10-24_0100Z"
    },
    "facts": {
      "title": "Insufficient authorization in shared channel membership sync allows remote cluster to remove users from arbitrary channels",
      "summary": "Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13, 11.4.x <= 11.4.3 fail to validate that a remote cluster has access to a channel before processing membership removal requests during shared channel membership sync, which allows a malicious remote cluster to remove any user from any channel, including private channels, via crafted membership sync messages targeting channels the remote cluster is not authorized to access. Mattermost Advisory ID: MMSA-2026-00576",
      "affected": [
        {
          "vendor": "Mattermost",
          "product": "Mattermost",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "11.5.0",
              "status": "affected",
              "versionType": "semver",
              "lessThanOrEqual": "11.5.1"
            },
            {
              "version": "10.11.0",
              "status": "affected",
              "versionType": "semver",
              "lessThanOrEqual": "10.11.13"
            },
            {
              "version": "11.4.0",
              "status": "affected",
              "versionType": "semver",
              "lessThanOrEqual": "11.4.3"
            },
            {
              "version": "11.6.0",
              "status": "unaffected"
            },
            {
              "version": "11.5.2",
              "status": "unaffected"
            },
            {
              "version": "10.11.14",
              "status": "unaffected"
            },
            {
              "version": "11.4.4",
              "status": "unaffected"
            }
          ]
        }
      ]
    }
  }
}