CVE-2026-9820

LOW CVSS 3.1: 3.8 EPSS 0.15%
Updated Jul 13, 2026
Mattermost
Parameter Value
CVSS 3.8 (LOW)
Affected Versions 10.11.0 — 11.7.3
Fixed In 10.11.20
Type CWE-862 (Missing Authorization)
Vendor Mattermost
Public PoC No

Mattermost versions 11.7.x <= 11.7.2, 10.11.x <= 10.11.19 fail to sanitize team objects returned by the scheme teams endpoint, which allows a user with the User Manager role to obtain invite links for private teams and use them to join or share access to those teams via the scheme teams API endpoint.. Mattermost Advisory ID: MMSA-2026-00671

Attack Parameters

Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Privileges Required
High
Admin privileges needed
User Interaction
None
No user interaction needed

Impact Assessment

Confidentiality
Low
Partial data leak
Integrity
Low
Partial data modification
Availability
None
No disruption

CVSS Vector v3.1

Vulnerable Products 2

Configuration From (including) Up to (excluding)
Mattermost Mattermost_Server
cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
10.11.0 10.11.20
Mattermost Mattermost_Server
cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
11.7.0 11.7.3