CVE-2026-0999
February 16, 2026
Mattermost versions 11.1.x <= 11.1.2, 10.11.x <= 10.11.9, 11.2.x <= 11.2.1 fail to properly validate login method restrictions which allows an authenticated user to bypass SSO-only login requirements via userID-based authentication. Mattermost Advisory ID: MMSA-2025-00548
Affected Packages
github.com/mattermost/mattermost (GO):
Affected version(s) >=v11.2.0 <v11.2.2Fix Suggestion:
Update to version v11.2.2github.com/mattermost/mattermost (GO):
Affected version(s) >=v11.1.0 <v11.1.3Fix Suggestion:
Update to version v11.1.3github.com/mattermost/mattermost/server/v8 (GO):
Affected version(s) >=v8.0.0-20230429093631-aac4f2337933 <v8.0.0-20251212052346-61651b0df7eaFix Suggestion:
Update to version v8.0.0-20251212052346-61651b0df7eagithub.com/mattermost/mattermost (GO):
Affected version(s) >=v10.11.0 <v10.11.10Fix Suggestion:
Update to version v10.11.10Related Resources (5)
Do you need more information?
Contact UsCVSS v4
Base Score:
5.3
Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
NONE
Privileges Required
LOW
User Interaction
NONE
Vulnerable System Confidentiality
LOW
Vulnerable System Integrity
LOW
Vulnerable System Availability
NONE
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
5.4
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
LOW
Integrity
LOW
Availability
NONE
Weakness Type (CWE)
Incorrect Implementation of Authentication Algorithm
EPSS
Base Score:
0.05
