Unrated
Guest user can upload files without permission across teams
CVE-2026-4265
First seen on SecPulse
Original description The description as published by the source.
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
Source: OSV.dev (Open Source Vulnerabilities) NVD GitHub Advisory OSV
References
- advisory github.com
- advisory mattermost.com
- advisory nvd.nist.gov