Mattermost group syncable endpoints allow privilege escalation via scheme_admin
CVE-2026-7387

8.8HIGH

Key Information:

Vendor

Mattermost
Status
Mattermost
Vendor
CVE Published:
12 June 2026

What is CVE-2026-7387?

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

Affected Version(s)

Mattermost 11.6.0 <= 11.6.1

Mattermost 11.5.0 <= 11.5.4

Mattermost 10.11.0 <= 10.11.15

References

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

CVSS V3.1

Score:
8.8
Severity:
HIGH
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
Low
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

winfunc
.