CVE-2026-0999

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

CVSS v3 5.4 MEDIUM

5.4^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 2.8 / Impact : 2.5

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required LOW

User Interaction NONE

Confidentiality Impact LOW

Integrity Impact LOW

Availability Impact NONE

Scope UNCHANGED

References

Link	Resource
https://mattermost.com/security-updates	Vendor Advisory

Configurations

Configuration 1 (hide)

OR	cpe:2.3:a:mattermost:mattermost_server::::::::
	cpe:2.3:a:mattermost:mattermost_server::::::::
	cpe:2.3:a:mattermost:mattermost_server::::::::

History

18 Feb 2026, 20:20

Type	Values Removed	Values Added
References	~~() https://mattermost.com/security-updates -~~	() https://mattermost.com/security-updates - Vendor Advisory
First Time		Mattermost Mattermost mattermost Server
CPE		cpe:2.3:a:mattermost:mattermost_server::::::::

18 Feb 2026, 17:52

Type	Values Removed	Values Added
Summary		(es) Las versiones de Mattermost 11.1.x <= 11.1.2, 10.11.x <= 10.11.9, 11.2.x <= 11.2.1 no validan correctamente las restricciones del método de inicio de sesión, lo que permite a un usuario autenticado eludir los requisitos de inicio de sesión solo por SSO mediante autenticación basada en ID de usuario. ID de aviso de Mattermost: MMSA-2025-00548

16 Feb 2026, 10:16

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-02-16 10:16

Updated : 2026-02-18 20:20

NVD link : CVE-2026-0999

Mitre link : CVE-2026-0999

CVE.ORG link : CVE-2026-0999

JSON object : View

Products Affected

mattermost

mattermost_server

CWE

CWE-303

Incorrect Implementation of Authentication Algorithm

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