Authenticated denial of service via unbounded plugin requests
Published Sep 22, 2026 · Updated Sep 22, 2026
Denial of service in Mattermost Server allows remote authenticated users to exhaust server memory through oversized plugin requests. The CSRF validation path for plugin endpoints reads a request body without enforcing a size limit, allowing attacker-controlled data to consume memory. A valid user session and a reachable plugin endpoint are required; affected branches are 11.7.0 through 11.7.10, 11.8.0 through 11.8.5, 11.9.0 through 11.9.1, and 11.10.0 through 11.10.1, with server unavailability as the bounded consequence.
Summary
What happened
Denial of service in Mattermost Server allows remote authenticated users to exhaust server memory through oversized plugin requests. The CSRF validation path for plugin endpoints reads a request body without enforcing a size limit, allowing attacker-controlled data to consume memory. A valid user session and a reachable plugin endpoint are required; affected branches are 11.7.0 through 11.7.10, 11.8.0 through 11.8.5, 11.9.0 through 11.9.1, and 11.10.0 through 11.10.1, with server unavailability as the bounded consequence.
The record
- CVE
- CVE-2026-96260
- Published
- Sep 22, 2026
- Updated
- Sep 22, 2026
- Vendor
- Mattermost
- Product
- Mattermost
- Classifications
- CWE-789, T1499
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Sep 22, 2026CVE publishedPublication date reported by the CVE source.
- Sep 22, 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=11.10.0 <=11.10.1
- Affected versionversion=11.7.0 <=11.7.10
- Affected versionversion=11.8.0 <=11.8.5
- Affected versionversion=11.9.0 <=11.9.1
What conditions does exploitation require?
What is affected?
Published CVSS scores
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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.
Activity data is delayed. The latest report is Sep 28, 2026.
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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