Mattermost Agents plugin logs unsanitized OpenAI API keys on authentication errors
Priority LOW 30CWE-532Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- High
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Information disclosure
- Confidentiality · integrity · availability
- High · None · None
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-532.
Summary
Mattermost Plugins versions <=11.6 10.18.11 11.3.6 11.6.5.0 fail to sanitize error responses from the OpenAI API before logging, which allows a user with access to server logs or support packets to obtain a valid or partially reconstructable OpenAI API key via inspection of mattermost.log entries generated during authentication failures. Mattermost Advisory ID: MMSA-2026-00609
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00459 40th percentileScored 2026-11-07
Fix Fixed Mattermost (Mattermost): 11.7.0, 10.11.19, 11.6.4 +1
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Mattermost | Mattermost | up to 10.18.11; up to 11.3.6; up to 11.6.5 | 11.7.0, 10.11.19, 11.6.4, 11.5.7 | Patch available | CNA |
- Mattermost VendorMattermost Affected up to 10.18.11; up to 11.3.6; up to 11.6.5 Fixed in 11.7.0, 10.11.19, 11.6.4, 11.5.7 Patch available CNA
Remediation
- Fix · CNA Mattermost (Mattermost) Fixed in 11.7.0, 10.11.19, 11.6.4, 11.5.7
Timeline
- 2026-10-02 Threatist record created from CVE-2026-9699
- 2026-10-03 Alias added: GHSA-gr4w-63r3-8h38
References
Advisory 1
More Mattermost vulnerabilities
- TI-2025-18933 Arbitrary file read in Mattermost Boards via import & export board archive CVSS 3.1CRITICAL 9.9
- TI-2019-15071 An issue was discovered in Mattermost Packages before 5.16.3. CVSS 3.1CRITICAL 9.8
- TI-2025-04465 Path Traversal Leading to RCE by Any Authenticated Mattermost User CVSS 3.1CRITICAL 9.9
- TI-2019-15074 An issue was discovered in Mattermost Desktop App before 4.3.0 on macOS. CVSS 3.1CRITICAL 9.8
- TI-2017-14068 An issue was discovered in Mattermost Server before 3.6.2. CVSS 3.1CRITICAL 9.8
- TI-2017-14060 An issue was discovered in Mattermost Server before 3.8.2, 3.7.5, and 3.6.7. CVSS 3.1CRITICAL 9.8
Sources
- CVE-2026-9699 · CVE Program
- CVE-2026-9699 · NVD
- FIRST EPSS
- GHSA-gr4w-63r3-8h38 · GitHub Advisory Database · CC BY 4.0
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