ABAC policy bypass via empty imports list
Published Sep 14, 2026 · Updated Sep 14, 2026
Incorrect authorization in Mattermost 11.7.0 through 11.7.7, 11.8.0 through 11.8.4, and 11.9.0 allows remote authenticated users to bypass ABAC. The PUT /api/v4/access_control_policies handler accepts an empty imports list and detaches the system-assigned parent instead of preserving its mandatory inheritance. A channel or team administrator with ABAC enabled can remove inherited access constraints, leaving locally defined policy rules to govern membership without the system policy.
Summary
What happened
Incorrect authorization in Mattermost 11.7.0 through 11.7.7, 11.8.0 through 11.8.4, and 11.9.0 allows remote authenticated users to bypass ABAC. The PUT /api/v4/access_control_policies handler accepts an empty imports list and detaches the system-assigned parent instead of preserving its mandatory inheritance. A channel or team administrator with ABAC enabled can remove inherited access constraints, leaving locally defined policy rules to govern membership without the system policy.
The record
- CVE
- CVE-2026-82920
- Published
- Sep 14, 2026
- Updated
- Sep 14, 2026
- Vendor
- Mattermost
- Product
- Mattermost
- Classifications
- Unavailable
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Sep 14, 2026CVE publishedPublication date reported by the CVE source.
- Sep 14, 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?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=11.7.0 <=11.7.7
- Affected versionversion=11.8.0 <=11.8.4
- Affected versionversion=11.9.0 <=11.9.0
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
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Public exploit references
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Technologies
Your stack
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Your stack
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