CVE-2026-9699 | BDVDB-2026-343453 Detail

MattermostMattermost

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

Impact#

Per CVSS v3.1: confidentiality impact high, integrity impact none, availability impact none. Attack vector: network.

Weaknesses#

CWE-532 Insertion of Sensitive Information into Log File

References#

https://mattermost.com/security-updates

Exploit#

No public exploit known

History#

Version 12026-06-26Record published in the CVE List.

Published

Published: 2026-06-26
Last modified: 2026-06-26

Vendor information

Vendor: Mattermost
Product: Mattermost

All Mattermost vulnerabilities

Score

6.8 Medium

EPSS

less than 1%, Very Low

Estimated chance of exploitation in the next 30 days. EPSS percentile: 40.1.

KEV

Not listed in the CISA Known Exploited Vulnerabilities catalog.

Impact

Information Disclosure

Action

No specific action is recorded in the source data. Check the references for vendor guidance.

Affected Systems

Vulnerable
<= 10.18.11
Fixed
Not stated
Vulnerable
<= 11.3.6
Fixed
Not stated
Vulnerable
<= 11.6.5
Fixed
Not stated
Vulnerable
Not stated
Fixed
11.7.0
Vulnerable
Not stated
Fixed
10.11.19
Vulnerable
Not stated
Fixed
11.6.4
Vulnerable
Not stated
Fixed
11.5.7

Scoring System

CVSS v4.0

Not available

CVSS v3.1

6.8 Medium

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

Metric breakdown
Attack Vector	Network
Attack Complexity	Low
Privileges Required	High
User Interaction	None
Scope	Changed
Confidentiality	High
Integrity	None
Availability	None

CVSS v3.0

Not available

CVSS v2

Not available

Source: CVE List v5 (record); CISA KEV (kev, action); FIRST EPSS (epss).