Team Search Misconfiguration in Mattermost Affects User Privacy
CVE-2026-18256

4.3MEDIUM

Key Information:

Vendor

Mattermost
Status
Mattermost
Vendor
CVE Published:
16 October 2026

What is CVE-2026-18256?

Certain versions of Mattermost contain a misconfiguration that allows authenticated users lacking the necessary permissions to access private team information through modified team search requests. This issue results in unintended exposure of private team IDs, names, and display names, compromising user privacy and potentially leading to unauthorized access to sensitive information.

Affected Version(s)

Mattermost 11.10.0

Mattermost 11.7.0 <= 11.7.9

Mattermost 11.9.0 <= 11.9.1

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

CERT PL
.