Cross-team ABAC policy removal via missing scope check
Published Aug 17, 2026 · Updated Aug 17, 2026
Incorrect authorization in Mattermost 11.7.0 through 11.7.6 and 11.8.0 through 11.8.3 allows remote authenticated users to remove ABAC assignments. The policy-unassign endpoint trusts a prior assignment selection and does not revalidate each target channel's current team before deleting its policy link. Exploitation requires team-administrator access, a channel moved after policy assignment, and a request that removes another team's access-control assignment.
Summary
What happened
Incorrect authorization in Mattermost 11.7.0 through 11.7.6 and 11.8.0 through 11.8.3 allows remote authenticated users to remove ABAC assignments. The policy-unassign endpoint trusts a prior assignment selection and does not revalidate each target channel's current team before deleting its policy link. Exploitation requires team-administrator access, a channel moved after policy assignment, and a request that removes another team's access-control assignment.
The record
- CVE
- CVE-2026-15754
- Published
- Aug 17, 2026
- Updated
- Aug 17, 2026
- Vendor
- Mattermost
- Product
- Mattermost
- Classifications
- CWE-863
- Attack vector
- network
- Privileges
- admin
Timeline
How it unfolded
- Aug 17, 2026CVE publishedPublication date reported by the CVE source.
- Aug 17, 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=11.7.0 <=11.7.6
- Affected versionversion=11.8.0 <=11.8.3
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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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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