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
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Privileges Required
Low
Basic privileges needed
User Interaction
None
No user interaction needed
Impact Assessment
Confidentiality
None
No data leak
Integrity
Low
Partial data modification
Availability
None
No disruption
CVSS Vector v3.1
Weakness Type (CWE)
Vulnerable Products 3
| Configuration | From (including) | Up to (excluding) |
|---|---|---|
|
Mattermost Mattermost_Server
cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
|
10.11.0
|
10.11.11
|
|
Mattermost Mattermost_Server
cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
|
11.2.0
|
11.2.3
|
|
Mattermost Mattermost_Server
cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
|
11.3.0
|
11.3.1
|