Mattermost: >> Mattermost Server Security Vulnerabilities
Mattermost versions 10.10.x <= 10.10.1 fail to properly sanitize user data during shared channel membership synchronization, which allows malicious or compromised remote clusters to access sensitive user information via unsanitized user objects. This vulnerability affects Mattermost Server instances with shared channels enabled.
CVSS Score
6.5
EPSS Score
0.0
Published
2025-09-15
Mattermost versions 10.8.x <= 10.8.3, 10.5.x <= 10.5.8, 9.11.x <= 9.11.17, 10.10.x <= 10.10.1, 10.9.x <= 10.9.3 fail to properly validate cache keys for link metadata which allows authenticated users to access unauthorized posts and poison link previews via hash collision attacks on FNV-1 hashing
CVSS Score
4.3
EPSS Score
0.0
Published
2025-09-15
Mattermost versions 10.8.x <= 10.8.3, 10.5.x <= 10.5.8, 9.11.x <= 9.11.17, 10.10.x <= 10.10.0, 10.9.x <= 10.9.3 fail to validate import data which allows a system admin to crash the server via the bulk import feature.
CVSS Score
4.9
EPSS Score
0.001
Published
2025-08-21
Mattermost versions 10.8.x <= 10.8.3, 10.5.x <= 10.5.8, 10.10.x <= 10.10.0, 10.9.x <= 10.9.3 fail to sanitize file names which allows users with file upload permission to overwrite file attachment thumbnails via path traversal in file streaming APIs.
CVSS Score
4.3
EPSS Score
0.001
Published
2025-08-21
Mattermost versions 10.8.x <= 10.8.3, 10.5.x <= 10.5.8, 9.11.x <= 9.11.17, 10.9.x <= 10.9.2 fail to sanitize the team invite ID in the POST /api/v4/teams/:teamId/restore endpoint which allows an team admin with no member invite privileges to get the team’s invite id.
CVSS Score
4.3
EPSS Score
0.0
Published
2025-08-21
Mattermost versions 10.8.x <= 10.8.3, 10.5.x <= 10.5.8, 9.11.x <= 9.11.17, 10.9.x <= 10.9.2, 10.10.x <= 10.10.0 fail to validate upload types in remote cluster upload sessions which allows a system admin to upload non-attachment file types via shared channels that could potentially be placed in arbitrary filesystem directories.
CVSS Score
6.8
EPSS Score
0.0
Published
2025-08-21
Mattermost versions 10.5.x <= 10.5.8 fail to validate access controls at time of access which allows user to read a thread via AI posts
CVSS Score
3.5
EPSS Score
0.0
Published
2025-08-21
Mattermost versions 10.5.x <= 10.5.8, 9.11.x <= 9.11.17 fail to properly validate authorization for team scheme role modifications which allows Team Admins to demote Team Members to Guests via the PUT /api/v4/teams/team-id/members/user-id/schemeRoles API endpoint.
CVSS Score
3.8
EPSS Score
0.0
Published
2025-08-21
Mattermost versions 10.8.x <= 10.8.3, 10.5.x <= 10.5.8, 9.11.x <= 9.11.17, 10.9.x <= 10.9.2 fails to sanitize path traversal sequences in template file destination paths, which allows a system admin to perform path traversal attacks via malicious path components, potentially enabling malicious file placement outside intended directories.
CVSS Score
6.8
EPSS Score
0.001
Published
2025-08-21
Mattermost Server versions 10.5.x <= 10.5.9 utilizing the Agents plugin fail to reject empty request bodies which allows users to trick users into clicking malicious links via post actions
CVSS Score
3.5
EPSS Score
0.0
Published
2025-08-21