Medium severity · published Nov 13, 2025
CVE-2025-11777
Cross-team channel membership access
4.3
CVSS
0.2%
EPSS
No
On KEV
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
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
Low
Integrity
None
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.2% · higher than 9% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
MA
Mattermost · Mattermost
10.11.0 through 10.11.3; 10.5.0 through 10.5.11 · source: vendor
MS
Mattermost Server · Mattermost
10.5.0 before 10.5.12; 10.11.0 before 10.11.4 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2025-11777
CVE.org
https://www.cve.org/CVERecord?id=CVE-2025-11777
Vendor Advisory
https://mattermost.com/security-updates
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