Mattermost Board Import Flaw Grants Unauthorized Admin Rights
CVE-2026-16044

3.9LOW

Key Information:

Vendor

Mattermost
Status
Mattermost
Vendor
CVE Published:
17 August 2026

What is CVE-2026-16044?

A security flaw in Mattermost allows guest users to be granted Board Admin privileges when performing a board archive import. This vulnerability arises from the failure of the application to adequately validate user roles during the import of specially crafted .boardarchive files. Consequently, unauthorized escalation of guest user permissions can pose significant security risks within the Mattermost platform.

Affected Version(s)

Mattermost 11.7.0 <= 11.7.6

Mattermost 10.11.0 <= 10.11.21

Mattermost 11.9.0

References

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

CVSS V3.1

Score:
3.9
Severity:
LOW
Confidentiality:
None
Integrity:
Low
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
Low
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

ilent0
.