Improper Data Sanitization in Mattermost API for Team Member Information
CVE-2026-3636

4.3MEDIUM

Key Information:

Vendor

Mattermost
Status
Mattermost
Vendor
CVE Published:
22 May 2026

What is CVE-2026-3636?

Mattermost versions 10.11.x through 11.6.x demonstrate a significant flaw in the handling of team member data through API calls. The system fails to appropriately sanitize data when serving requests from users lacking elevated permissions. As a result, unauthorized users may exploit various team API endpoints to access sensitive information about team members' roles and attributes, posing serious risks to user privacy and data integrity.

Affected Version(s)

Mattermost 11.6.0

Mattermost 11.5.0 <= 11.5.3

Mattermost 11.4.0 <= 11.4.4

References

https://mattermost.com/security-updates
vendor-advisory

CVSS V3.1

Score:
4.3
Severity:
MEDIUM
Confidentiality:
Low
Integrity:
None
Availability:
Low
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
Low
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

runup
.