Mattermost <=11.3.0/<=11.2.2 run_create Perm Bypass Unauthorized Playbook Run
CVE-2026-26304 Published on March 16, 2026
Permission Bypass in Playbook Run Creation
Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2 fail to verify run_create permission for empty playbookId, which allows team members to create unauthorized runs via the playbook run API. Mattermost Advisory ID: MMSA-2025-00542
Vulnerability Analysis
CVE-2026-26304 is exploitable with network access, and requires small amount of user privileges. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality, with no impact on integrity, and no impact on availability.
Weakness Type
What is an AuthZ Vulnerability?
The software performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check. This allows attackers to bypass intended access restrictions.
CVE-2026-26304 has been classified to as an AuthZ vulnerability or weakness.
Products Associated with CVE-2026-26304
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Affected Versions
Mattermost:- Version 11.3.0, <= 11.3.0 is affected.
- Version 11.2.0, <= 11.2.2 is affected.
- Version 11.4.0 is unaffected.
- Version 11.3.1 is unaffected.
- Version 11.2.3 is unaffected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.