CVE-2026-14259

Mattermost versions 11.9.x <= 11.9.0, 11.8.x <= 11.8.4, 11.7.x <= 11.7.7, 10.11.x <= 10.11.22 fail to enforce board creation permissions when importing archive files which allows an authenticated non-guest team member to create Open or Private boards despite administrator restrictions via importing a crafted .boardarchive file. Mattermost Advisory ID: MMSA-2026-00712

  • Published Sep 14, 2026
  • CVSS 4.3 medium
  • 0.2% chance of exploitation in the next 30 days (EPSS)

Affected software

CVE-2026-14259 at the National Vulnerability Database