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CVE-2026-0999mediumCWE-303

Authentication bypass via userID login when email and username login are disabled

13Vexday Risk Score

No sign of exploitation. No public exploitation artifact known so far.

ssvc Trackcvss 5.4epss 0.2%
exploitation probability
0.2%top 93% of all CVEs
observed exploitation
nono source reports it
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:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
Affected products
Mattermost · Mattermost