Administrator SSRF via unfiltered OAuth endpoints
Published Sep 22, 2026 · Updated Sep 22, 2026
Server-side request forgery in affected Mattermost 11.7.x through 11.10.x servers allows remote authenticated users to read internal responses. The OAuth client setup path omits the internal-connection filter when fetching administrator-configured token and userinfo endpoint URLs in 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. System Administrator privileges and control of an OAuth configuration are required; the resulting requests expose response bodies from internal network addresses.
Summary
What happened
Server-side request forgery in affected Mattermost 11.7.x through 11.10.x servers allows remote authenticated users to read internal responses. The OAuth client setup path omits the internal-connection filter when fetching administrator-configured token and userinfo endpoint URLs in 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. System Administrator privileges and control of an OAuth configuration are required; the resulting requests expose response bodies from internal network addresses.
The record
- CVE
- CVE-2026-96259
- Published
- Sep 22, 2026
- Updated
- Sep 22, 2026
- Vendor
- Mattermost
- Product
- Mattermost
- Classifications
- T1190
- Attack vector
- network
- Privileges
- admin
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
No CVSS assessment is available in this record.
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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
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Technologies
Your stack
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Your stack
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