Permission Verification Flaw in Mattermost by Mattermost
CVE-2026-26304

4.3MEDIUM

Key Information:

Vendor

Mattermost
Status
Mattermost
Vendor
CVE Published:
16 March 2026

What is CVE-2026-26304?

Certain versions of Mattermost, specifically 11.3.x up to 11.3.0 and 11.2.x up to 11.2.2, are vulnerable due to a flaw in verifying permissions related to the playbook run API. This weakness allows team members to create unauthorized runs by exploiting the absence of a valid playbookId, leading to potential misuse of system capabilities. Users of these versions are advised to upgrade to mitigate this risk.

Affected Version(s)

Mattermost 11.3.0

Mattermost 11.2.0 <= 11.2.2

Mattermost 11.4.0

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

0x7oda7123
.