Plugin Handler Panic in Mattermost Affected Versions by Mattermost
CVE-2026-86348

4.3MEDIUM

Key Information:

Vendor

Mattermost
Status
Mattermost
Vendor
CVE Published:
14 September 2026

What is CVE-2026-86348?

A vulnerability in Mattermost allows authenticated users to induce crashes in the plugin system due to improper handling of post-action requests. Specifically, if a user submits a post-action request with an unexpected field type, it triggers a handler panic that the application fails to recover from. This issue affects several versions of Mattermost, making it critical for users to apply updates to ensure platform stability and functionality.

Affected Version(s)

Mattermost <=11.9 11.0.9 11.4.8 11.7.7 10.22.11.0 <= 11.9 11.0.9 11.4.8 11.7.7 10.22.11.0

Mattermost 11.10.0

Mattermost 11.9.1

References

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

CVSS V3.1

Score:
4.3
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
.