Mattermost <=11.6.1 Auth Bypass via scheme_admin flag -> Priv Escalation
CVE-2026-7387 Published on June 12, 2026
Mattermost group syncable endpoints allow privilege escalation via scheme_admin
Mattermost versions 11.6.x <= 11.6.1, 11.5.x <= 11.5.4, 10.11.x <= 10.11.15, 10.11.x <= 10.11.16 Mattermost fails to require role-management authorization when setting the scheme_admin flag on group syncable link and patch endpoints, which allows a user with group-link permissions to escalate themselves and group members to team or channel admin via crafted API requests.. Mattermost Advisory ID: MMSA-2026-00665
Vulnerability Analysis
CVE-2026-7387 can be exploited 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 be very high.
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-2026-7387 has been classified to as an AuthZ vulnerability or weakness.
Products Associated with CVE-2026-7387
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Affected Versions
Mattermost:- Version 11.6.0, <= 11.6.1 is affected.
- Version 11.5.0, <= 11.5.4 is affected.
- Version 10.11.0, <= 10.11.15 is affected.
- Version 10.11.0, <= 10.11.16 is affected.
- Version 11.7.0 is unaffected.
- Version 11.6.2 is unaffected.
- Version 11.5.5 is unaffected.
- Version 10.11.16 is unaffected.
- Version 10.11.17 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.