What is CVE-2026-12284?

CVE-2026-12284 is a low-severity vulnerability in Mattermost, classified under Origin Validation Error. CVSS score: 3.7/10. Published 2026-09-17.

How severe is CVE-2026-12284?

Low severity. CVSS v3 base score is 3.7 out of 10.

Vulnerability in Mattermost

CVE-2026-12284

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 v3 metric

CVSS v3 base score 3.7 (Low). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L.

Affected products

Mattermost

Weakness classification (CWE)

CWE-346 — Origin Validation Error

References

responsibledisclosure@mattermost.com (vendor-advisory)

Frequently asked questions

What is CVE-2026-12284?: CVE-2026-12284 is a low-severity vulnerability in Mattermost, classified under Origin Validation Error. CVSS score: 3.7/10. Published 2026-09-17.
How severe is CVE-2026-12284?: Low severity. CVSS v3 base score is 3.7 out of 10.