Unauthorized private-team access via unsanitized retention responses
Published Sep 14, 2026 · Updated Sep 14, 2026
Information disclosure in affected Mattermost server releases allows remote authenticated users to obtain private-team invite secrets. The data retention policy teams handler returns unsanitized Team objects, exposing each private team's invite_id and email fields to callers. The caller needs only read-only Data Retention Policy permission; the leaked invite_id permits unauthorized team membership and access.
Summary
What happened
Information disclosure in affected Mattermost server releases allows remote authenticated users to obtain private-team invite secrets. The data retention policy teams handler returns unsanitized Team objects, exposing each private team's invite_id and email fields to callers. The caller needs only read-only Data Retention Policy permission; the leaked invite_id permits unauthorized team membership and access.
The record
- CVE
- CVE-2026-91181
- 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=10.11.0 <=10.11.22
- 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
No CVSS assessment is available in this record.
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
No sourced classifications are available.
Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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