CVE-2025-11777 - CVE House
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Status published Low CVE-2025-11777

Cross-team channel membership access

Vulnerability Description

Mattermost versions 10.11.x <= 10.11.3, 10.5.x <= 10.5.11 fail to properly validate team membership permissions in the Add Channel Member API which allows users from one team to access user metadata and channel membership information from other teams via the API endpoint

Impact Analysis

Refer to official advisory for detailed impact metrics.

Remediation

Ensure systems are updated to the latest vendor-supplied patch levels.

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Credits & Attribution

The following person or organization is credited with identifying this vulnerability, as recorded in the NVD database:

  • Xiangyu Guo

References

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Affected Vendor

Affected Software

Mattermost
Vulnerable Versions:
10.11.0, 10.5.0, 11.0.0, 10.11.4, 10.5.12

Timeline

Official Publish: November 13th, 2025
Last Modified: November 13th, 2025
Added to House: July 22nd, 2026

CVSS Vectors

V3: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N

Weaknesses (CWE)

CWE-863

MITRE ATT&CK TTPs

T1190 Exploit Public-Facing Application
Initial Access
T1078 Valid Accounts
Persistence
T1548 Abuse Elevation Control Mechanism
Privilege Escalation
T1021 Remote Services
Lateral Movement
T1098 Account Manipulation
Defense Evasion