Property Management Flaw in Mattermost Affects Multiple Versions
CVE-2026-9812

6.5MEDIUM

Key Information:

Vendor

Mattermost
Status
Mattermost
Vendor
CVE Published:
14 September 2026

What is CVE-2026-9812?

Mattermost includes a vulnerability where versions 10.11.22 and 11.7.x through 11.9.x fail to properly validate property fields during updates. This flaw allows an authenticated user with property-management access to inadvertently crash the Playbooks plugin by referencing a property field from a different run via a REST request. This could lead to significant disruptions in service and necessitates prompt attention to ensure secure functionality.

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

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

alimursaliyev
.