Guest User Permission Flaw in Mattermost by Mattermost
CVE-2025-10545

3.1LOW

Key Information:

Vendor

Mattermost
Status
Mattermost
Vendor
CVE Published:
16 October 2025

What is CVE-2025-10545?

Mattermost experiences a critical flaw in its user permission system, specifically affecting versions 10.5.x up to 10.5.10 and 10.11.x up to 10.11.2. This vulnerability permits guest users to erroneously add team members to private channels by exploiting the /api/v4/channels/{channel_id}/members endpoint. This oversight in permission validation may lead to unauthorized access and compromised privacy for users, stressing the importance of reviewing and tightening guest user permissions within Mattermost.

Affected Version(s)

Mattermost 10.5.0 <= 10.5.10

Mattermost 10.11.0 <= 10.11.2

Mattermost 10.12.0

References

https://mattermost.com/security-updates

CVSS V3.1

Score:
3.1
Severity:
LOW
Confidentiality:
Low
Integrity:
None
Availability:
Low
Attack Vector:
Network
Attack Complexity:
High
Privileges Required:
Low
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

lordwillmore
JSON
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CVE-2025-10545 : Guest User Permission Flaw in Mattermost by Mattermost