Is CVE-2026-8683 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-8683 being exploited in the wild.

How severe is CVE-2026-8683?

Medium severity, with a CVSS score of 6.5, published 15 June 2026.

Which products and versions are affected?

Mattermost Desktop App <= 6.1, 5.5.13.0.

Is there a fix for CVE-2026-8683?

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-2026-8683 attacked?

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

Am I affected by CVE-2026-8683?

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-2026-8683: Mattermost Desktop App denial of service via long URLs

Q: Is there a fix for CVE-2026-8683?

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-2026-8683 attacked?

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

Q: Am I affected by CVE-2026-8683?

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-2026-8683 · Severity: medium · CVSS 6.5 · Published 2026-06-15

A vulnerability in the Mattermost Desktop application allows a malicious server owner to crash a user's app. By forcing the application to open an excessively long web link, the software becomes overwhelmed and stops responding. This can lead to a denial of service, disrupting communication and business operations for affected users.

Technologies: Mattermost Desktop App. Vendors: Mattermost.

Quick answers

Is CVE-2026-8683 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-8683 being exploited in the wild.
How severe is CVE-2026-8683?: Medium severity, with a CVSS score of 6.5, published 15 June 2026.
Which products and versions are affected?: Mattermost Desktop App <= 6.1, 5.5.13.0.
Is there a fix for CVE-2026-8683?: 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-2026-8683 attacked?: It is attacked over the network, in a network appliance.
Am I affected by CVE-2026-8683?: 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 throttle or limit the length of URLs passed to the window.open function, leading to an 'Allocation of Resources Without Limits or Throttling' (CWE-770) condition. A malicious server owner can exploit this by including a script that calls window.open with an exceptionally large URL string. This results in an application crash (Denial of Service). The attack requires user interaction to connect to or interact with the malicious server but does not require special privileges. The issue is addressed in Mattermost's security updates.

Affected products

Mattermost Desktop App <= 6.1, 5.5.13.0

Timeline

2026-06-15: disclosed
2026-06-15: advisory

References

https://mattermost.com/security-updates

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