CVE-2026-4265CWE-863

Guest user can upload files without permission across teams

Medium · published March 16, 2026

CVSS v3.1
4.3
EPSS
0%
Percentile
30.7
In the wild
Unconfirmed
What it is

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

The record
Technical detail
CVSS v3.1
4.3 · MEDIUM
Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
CVSS v4.0
Not supplied
EPSS
0.00379 · 30.7th percentile
Weakness
CWE-863 · Incorrect Authorization
Published
2026-03-16T12:07Z
EPSS history
Timeline
  • 16 MAR 12:07Z
    Guest user can upload files without permission across teams
    cvelistv5