CVE-2026-4265
Guest user can upload files without permission across teams
CVSS Score
4.3
EPSS Score
0.0%
EPSS Percentile
0th
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
| CWE | CWE-863 |
| Vendor | mattermost |
| Product | mattermost |
| Published | Mar 16, 2026 |
| Last Updated | Mar 16, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
None
Affected Versions
Mattermost / Mattermost
11.3.0 ≤ 11.3.0 11.2.0 ≤ 11.2.2 10.11.0 ≤ 10.11.10
Credits
0x7oda7123