CVE-2026-0999

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

CVSS 5.4 MEDIUMEPSS 0.2%CWE-303

Vexday Risk Score

13Low

SSVC decision (CISA)

Track

No exploitation signal → monitor

CVSS 5.4EPSS 0.2%KEV nãoPoC —Nuclei —Metasploit —Patch referenciado

Lifecycle

16 Feb 2026Published on NVD

Recommendation: Monitor — no exploitation signal at the moment.

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

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References

https://mattermost.com/security-updates