CVE-2026-9699

Mattermost Agents plugin logs unsanitized OpenAI API keys on authentication errors

Published Jun 26, 2026 CVSS 3.1 · 6.8 Medium EPSS < 1% KEV · Not listed
Description
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

Remediation

Vendor Solution

Update Mattermost Plugins to versions 11.7.0, 10.11.19, 11.6.4, 11.5.7 or higher.

Tracking

Sign in to view the affected projects.

Advisories

No advisories available
References
History
Type Values Removed Values Added
First Time appeared Mattermost
Mattermost mattermost
Vendors & Products Mattermost
Mattermost mattermost
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description 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
Title Mattermost Agents plugin logs unsanitized OpenAI API keys on authentication errors
Weaknesses CWE-532
References
Metrics cvssV3_1

{'score': 6.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:N/A:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
Mattermost
Published
Updated
Jun 26, 2026, 3:40 PM
Reserved
May 27, 2026, 12:08 PM
Status
Awaiting Analysis
Published
Jun 26, 2026, 3:16 PM
Modified
Jun 26, 2026, 4:16 PM