CVE-2026-9699

Mattermost Agents plugin logs unsanitized OpenAI API keys on authentication errors

CVSS 6.8 MEDIUMEPSS 0.3%CWE-532

Vexday Risk Score

13Low

SSVC decision (CISA)

Track

No exploitation signal → monitor

CVSS 6.8EPSS 0.3%KEV nãoPoC —Nuclei —Metasploit —Patch referenciado

Lifecycle

26 Jun 2026Published on NVD

Recommendation: Monitor — no exploitation signal at the moment.

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

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:N/A:N

Affected products

Mattermost · Mattermost

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References

https://mattermost.com/security-updates