Is CVE-2026-9602 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-9602 being exploited in the wild.

How severe is CVE-2026-9602?

Medium severity, with a CVSS score of 6.5, published 17 July 2026.

Which products and versions are affected?

Mattermost Desktop App <=6.2, 6.0.2, 5.6.13.0.

Is there a fix for CVE-2026-9602?

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-2026-9602 attacked?

It is attacked over the network, in a network appliance.

Am I affected by CVE-2026-9602?

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.

CVE-2026-9602: Mattermost Desktop App denial of service via malformed payload

Q: Is there a fix for CVE-2026-9602?

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.

Q: How is CVE-2026-9602 attacked?

It is attacked over the network, in a network appliance.

Q: Am I affected by CVE-2026-9602?

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.

CVE-2026-9602 · Severity: medium · CVSS 6.5 · Published 2026-07-17

A vulnerability in the Mattermost Desktop App allows a malicious server owner to crash the application on a user's computer. This occurs because the desktop software does not properly check the data it receives from the web server. An exploit would result in a denial of service, preventing employees from using the communication platform until the application is restarted or patched.

Technologies: Mattermost Desktop App. Vendors: Mattermost.

Quick answers

Is CVE-2026-9602 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-9602 being exploited in the wild.
How severe is CVE-2026-9602?: Medium severity, with a CVSS score of 6.5, published 17 July 2026.
Which products and versions are affected?: Mattermost Desktop App <=6.2, 6.0.2, 5.6.13.0.
Is there a fix for CVE-2026-9602?: 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-2026-9602 attacked?: It is attacked over the network, in a network appliance.
Am I affected by CVE-2026-9602?: 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 suffers from an uncontrolled resource consumption vulnerability (CWE-400) due to insufficient validation of payloads sent from the Mattermost Web App. A malicious server administrator can send a malformed method payload to the client application, triggering a crash. This is a network-based attack requiring low privileges (server owner status) but no user interaction. The vulnerability is addressed in versions 6.3.0, 6.2.1.0, and 5.13.7.0.

Affected products

Mattermost Desktop App <=6.2, 6.0.2, 5.6.13.0

Timeline

2026-07-17: disclosed
2026-07-17: advisory

References

https://mattermost.com/security-updates

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