CVE-2026-0999 MEDIUM

CVE-2026-0999: Authentication bypass via userID login when email and username login are disabled

Vendor Mattermost
Product Mattermost
Weakness CWE-303
Published February 16, 2026
Last update February 17, 2026
View on NVD All CVEs

CVSS base score

5.4/10
Attack vector Network
Attack complexity Low
Privileges required Low
User interaction None
Confidentiality Low
Integrity Low

CVSS vector

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

What the vulnerability does

01Description

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

Key dates

02Disclosure timeline

February 16, 2026 CVE published
February 17, 2026 Record updated