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

No CVSS v4.0

Attack Vector Network

Attack Complexity Low

Privileges Required Low

Scope Unchanged

Confidentiality Impact Low

Integrity Impact Low

Availability Impact None

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

The EPSS score is 0.00039.

Exploitation none

Automatable no

Technical Impact partial

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions
Mattermost Mattermost unaffected
Version Status Constraints
11.1.0 affected ≤ 11.1.2
10.11.0 affected ≤ 10.11.9
11.2.0 affected ≤ 11.2.1
11.3.0 unaffected —
11.1.3 unaffected —
10.11.10 unaffected —
11.2.2 unaffected —

Configuration 1 [-]

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

No data.

OpenCVE Enrichment is a feature of OpenCVE that uses AI to automatically link vendors and products to CVEs. Learn more on GitHub.

Vendors Products
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Project Subscriptions

Vendors Products
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Mattermost Server Subscribe
Advisories
Source ID Title
Github GHSA Github GHSA GHSA-3c9r-7f29-qp32 Mattermost fails to properly validate login method restrictions
Fixes

Solution

Update Mattermost to versions 11.3.0, 11.1.3, 10.11.10, 11.2.2 or higher.

Workaround

No workaround given by the vendor.

References
Link Providers
https://mattermost.com/security-updates cve-icon cve-icon
History

Wed, 18 Feb 2026 20:30:00 +0000

Type Values Removed Values Added
First Time appeared Mattermost mattermost Server
CPEs cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
Vendors & Products Mattermost mattermost Server

Tue, 17 Feb 2026 17:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Mon, 16 Feb 2026 12:15:00 +0000

Type Values Removed Values Added
First Time appeared Mattermost
Mattermost mattermost
Vendors & Products Mattermost
Mattermost mattermost

Mon, 16 Feb 2026 10:00:00 +0000

Type Values Removed Values Added
Description 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
Title Authentication bypass via userID login when email and username login are disabled
Weaknesses CWE-303
References
Metrics cvssV3_1

{'score': 5.4, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N'}

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: Mattermost

Published:

Updated: 2026-02-17T16:53:07.181Z

Reserved: 2026-01-15T15:59:41.357Z

Link: CVE-2026-0999

cve-icon Vulnrichment

Updated: 2026-02-17T16:53:03.665Z

cve-icon NVD

Status : Analyzed

Published: 2026-02-16T10:16:08.140

Modified: 2026-02-18T20:20:07.833

Link: CVE-2026-0999

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-02-16T12:00:59Z

Weaknesses