Private-post disclosure via unauthorized cache deduplication
Published Jul 18, 2025 · Updated Aug 7, 2025
Authorization bypass in affected Mattermost 9.11 and 10.x releases allows remote authenticated users to read private-channel posts. The CreatePost deduplication path resolves a guessed PendingPostID with GetSinglePost, returning the cached post without checking channel access. Exploitation requires a valid account and a recently created post's PendingPostID; the demonstrated consequence is disclosure of that post.
Summary
What happened
Authorization bypass in affected Mattermost 9.11 and 10.x releases allows remote authenticated users to read private-channel posts. The CreatePost deduplication path resolves a guessed PendingPostID with GetSinglePost, returning the cached post without checking channel access. Exploitation requires a valid account and a recently created post's PendingPostID; the demonstrated consequence is disclosure of that post.
The record
- CVE
- CVE-2025-6226
- Published
- Jul 18, 2025
- Updated
- Aug 7, 2025
- Vendor
- Mattermost
- Product
- Mattermost
- Classifications
- CWE-306, T1213.005
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Jul 18, 2025CVE publishedPublication date reported by the CVE source.
- Aug 7, 2025Record 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=10.5.0 <=10.5.6
- Affected versionversion=10.7.0 <=10.7.3
- Affected versionversion=10.8.0 <=10.8.1
- Affected versionversion=9.11.0 <=9.11.16
What conditions does exploitation require?
What is affected?
Published CVSS scores
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
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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