Team-admin member demotion via missing authorization
Published Mar 16, 2026 · Updated Mar 16, 2026
Incorrect authorization in Mattermost 10.11.0 through 10.11.10 allows remote authenticated users to demote members to guests as team administrators. The team member roles API endpoint accepts a guest-role assignment from team administrators without enforcing the permission required for that role change. Exploitation requires team-administrator access and can remove a member's ordinary team permissions, without reported server compromise or service interruption.
Summary
What happened
Incorrect authorization in Mattermost 10.11.0 through 10.11.10 allows remote authenticated users to demote members to guests as team administrators. The team member roles API endpoint accepts a guest-role assignment from team administrators without enforcing the permission required for that role change. Exploitation requires team-administrator access and can remove a member's ordinary team permissions, without reported server compromise or service interruption.
The record
- CVE
- CVE-2026-26230
- Published
- Mar 16, 2026
- Updated
- Mar 16, 2026
- Vendor
- Mattermost
- Product
- Mattermost
- Classifications
- CWE-863, T1531
- Attack vector
- network
- Privileges
- admin
Timeline
How it unfolded
- Mar 16, 2026CVE publishedPublication date reported by the CVE source.
- Mar 16, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
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- Affected versionversion=10.11.0 <=10.11.10
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
What attackers are doing with it
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Public exploit references
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Technologies
Your stack
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Your stack
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