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CVE-2026-26230

LOW CVSS 3.1: 3.8 EPSS 0.03%
Updated Mar 18, 2026
Mattermost
Parameter Value
CVSS 3.8 (LOW)
Affected Versions 10.11.0 — 10.11.11
Fixed In 10.11.11
Type CWE-863 (Incorrect Authorization)
Vendor Mattermost
Public PoC No

Mattermost versions 10.11.x <= 10.11.10 fail to properly validate permission requirements in the team member roles API endpoint which allows team administrators to demote members to guest role. Mattermost Advisory ID: MMSA-2025-00531

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 1

Configuration From (including) Up to (excluding)
Mattermost Mattermost_Server
cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
10.11.0 10.11.11