CVE-2026-1046
Published: 16 February 2026
Summary
CVE-2026-1046 is a high-severity Improper Authorization in Handler for Custom URL Scheme (CWE-939) vulnerability in Mattermost Mattermost Desktop. Its CVSS base score is 7.6 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Client Execution (T1203); ranked at the 13.8th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
Threat & Defense at a Glance
Threat & Defense Details
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Vulnerability in desktop client allows malicious server to trigger arbitrary executable execution via Help menu (user interaction), directly mapping to client-side exploitation and command execution techniques.
NVD Description
Mattermost Desktop App versions <=6.0 6.2.0 5.2.13.0 fail to validate help links which allows a malicious Mattermost server to execute arbitrary executables on a user’s system via the user clicking on certain items in the Help menu Mattermost Advisory ID:…
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MMSA-2026-00577
Deeper analysisAI
CVE-2026-1046 is a vulnerability in the Mattermost Desktop App affecting versions <=6.0, 6.2.0, and 5.2.13.0. The app fails to validate help links, which enables a malicious Mattermost server to execute arbitrary executables on a user's system when the user clicks on certain items in the Help menu. Published on 2026-02-16, the issue is rated 7.6 on the CVSS v3.1 scale (AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:N/A:L) and is associated with CWE-939.
An attacker who controls a Mattermost server can exploit this vulnerability against users connected to that server. Exploitation requires low privileges (PR:L) on the server side, user interaction (UI:R) by clicking Help menu items, and occurs over the network (AV:N). Successful exploitation allows execution of arbitrary executables on the victim's system, potentially leading to high confidentiality impacts and low availability disruption, with a scope change due to the privileged execution context.
Mattermost Advisory ID MMSA-2026-00577 provides details on mitigation. Security practitioners should refer to https://mattermost.com/security-updates for patch information and remediation guidance.
Details
- CWE(s)