GHSA-xpvf-6qcc-9jqcMediumCVSS 4.3

Mattermost fails to validate team-specific upload_file permissions

Published
March 16, 2026
Last Modified
March 18, 2026

🔗 CVE IDs covered (1)

CVE-2026-4265 →

📋 Description

Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 fail to validate team-specific upload_file permissions which allows a guest user to post files in channels where they lack upload_file permission via uploading files in a team where they have permission and reusing the file metadata in a POST request to a different team. Mattermost Advisory ID: MMSA-2025-00553

🎯 Affected products5

  • go/github.com/mattermost/mattermost/server/v8:< 8.0.0-20260107144005-c7f6efdfb035
  • go/github.com/mattermost/mattermost-server:< 5.3.2-0.20260107144005-c7f6efdfb035
  • go/github.com/mattermost/mattermost-server:>= 10.11.0-rc1, < 10.11.11
  • go/github.com/mattermost/mattermost-server:>= 11.2.0-rc1, < 11.2.3
  • go/github.com/mattermost/mattermost-server:>= 11.3.0-rc1, < 11.3.1

🔗 References (4)