Quick answers
- Is CVE-2026-4643 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-4643 being exploited in the wild.
- How severe is CVE-2026-4643?
- Low severity, with a CVSS score of 3.5, published 18 May 2026.
- Which products and versions are affected?
- Mattermost Desktop App <=6.1, 6.0.1, 5.4.13.0.
- Is there a fix for CVE-2026-4643?
- No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
- How is CVE-2026-4643 attacked?
- It is attacked over the network, in a network appliance.
- Am I affected by CVE-2026-4643?
- Check whether you run Mattermost Desktop App at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
The Mattermost Desktop App fails to properly sanitize or restrict server-rendered content from interacting with the underlying application view. Specifically, the application does not prevent the renderer context from invoking the window.close() method. An attacker controlling a malicious server or a malicious plugin can trigger this method to force the desktop client to close. This vulnerability is classified as an improper check for unusual or exceptional conditions (CWE-754). Exploitation requires a network-connected attacker with low privileges and some user interaction, resulting in a client-side denial of service.
Affected products
- Mattermost Desktop App <=6.1, 6.0.1, 5.4.13.0
Timeline
- 2026-05-18: disclosed: NVD publication date
- 2026-05-18: advisory: Mattermost Advisory MMSA-2026-00633 published