Mattermost Desktop App <=6.2.2.0 IPC Sender Validation Bypass in leaveCall
CVE-2026-12284 Published on September 17, 2026
Mattermost Desktop App Missing IPC Sender Validation in Calls Leave Handler
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
Vulnerability Analysis
CVE-2026-12284 is exploitable with network access, and does not require authorization privileges or user interaction. This vulnerability is consided to have a high level of attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity, and a small impact on availability.
Weakness Type
Origin Validation Error
The software does not properly verify that the source of data or communication is valid.
Products Associated with CVE-2026-12284
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Affected Versions
Mattermost:- Before and including 6.2.2 is affected.
- Version 6.3.0 is unaffected.
- Version 6.2.3.0 is unaffected.