Low severity · published Sep 17, 2026
CVE-2026-12284
Mattermost Desktop App Missing IPC Sender Validation in Calls Leave Handler
3.7
CVSS
0.2%
EPSS
No
On KEV
Description
Mattermost Desktop App versions <=6.2 6.2.2.0 fails to validate the IPC sender in the leaveCall handler which allows a malicious or compromised Mattermost server (or a user with script access to a connected server view) to disconnect an active call belonging to a different connected server via the desktopAPI.leaveCall IPC message. Mattermost Advisory ID: MMSA-2026-00699
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
Attack vector
Network
Complexity
High
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
Low
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.2% · higher than 6% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
MA
Mattermost · Mattermost
through 6.2.2 · source: vendor
MD
Mattermost Desktop · Mattermost
6.2.0 before 6.2.3 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-12284
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-12284
Vendor Advisory
https://mattermost.com/security-updates
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