VULNERABILITY INTELLIGENCE

CVE-2026-4265

CVSS score4.3 MEDIUM
EPSS probability0.23%
CISA KEVNot currently listed
Published2026-03-16
Last modified2026-06-17
CVSS vectorCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N

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

Weakness classification

  • responsibledisclosure@mattermost.com: CWE-863

Primary references