Board Creation Permissions Vulnerability in Mattermost by Mattermost
CVE-2026-14259

4.3MEDIUM

Key Information:

Vendor

Mattermost
Status
Mattermost
Vendor
CVE Published:
14 September 2026

What is CVE-2026-14259?

Certain versions of Mattermost contain a permissions misconfiguration that allows authenticated non-guest team members to create open or private boards when importing specially crafted archive files. This bypasses administrative restrictions, which exposes the application to potential misuse through unauthorized board creation. Proper access controls are essential to mitigate this risk, and users are urged to apply the latest security updates to prevent exploitation.

Affected Version(s)

Mattermost 11.9.0

Mattermost 11.8.0 <= 11.8.4

Mattermost 11.7.0 <= 11.7.7

References

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

CVSS V3.1

Score:
4.3
Severity:
MEDIUM
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

angelatanasov5ac9f8
.