User Data Exposure in Mattermost Server Due to Insufficient Sanitization
CVE-2025-9076

6.5MEDIUM

Key Information:

Vendor

Mattermost
Status
Mattermost
Vendor
CVE Published:
15 September 2025

What is CVE-2025-9076?

Mattermost Server versions 10.10.x prior to 10.10.2 have a vulnerability that arises from inadequate sanitization of user data during the synchronization of shared channel memberships. This flaw enables malicious or compromised remote clusters to access sensitive user information through unsanitized user objects, posing a significant security risk for organizations utilizing shared channels.

Affected Version(s)

Mattermost 10.10.0 <= 10.10.1

Mattermost 10.11.0

Mattermost 10.10.2

References

https://mattermost.com/security-updates

CVSS V3.1

Score:
6.5
Severity:
MEDIUM
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
High
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

daw10
.
CVE-2025-9076 : User Data Exposure in Mattermost Server Due to Insufficient Sanitization