Medium severity · published Sep 15, 2025
CVE-2025-9076
Mattermost Server exposes sensitive user credentials during shared channel membership synchronization
6.5
CVSS
0.3%
EPSS
No
On KEV
Description
Mattermost versions 10.10.x <= 10.10.1 fail to properly sanitize user data during shared channel membership synchronization, which allows malicious or compromised remote clusters to access sensitive user information via unsanitized user objects. This vulnerability affects Mattermost Server instances with shared channels enabled.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
High
Integrity
None
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 18% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
MA
Mattermost · Mattermost
10.10.0 through 10.10.1 · source: vendor
MS
Mattermost Server · Mattermost
10.10.0 before 10.10.2 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2025-9076
CVE.org
https://www.cve.org/CVERecord?id=CVE-2025-9076
Vendor Advisory
https://mattermost.com/security-updates
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