What’s Vulnerable › Vulnerabilities
CVE-2026-75588: Mattermost Desktop App plugin popout scheme validation bypass
- Severity: low (CVSS 2.6 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 0.2% probability of exploitation in the next 30 days
- Public exploit or detection template: none known
- Published: 2026-09-17 · updated 2026-10-13
- Weakness: CWE-1287
Description
Mattermost Desktop App versions <=6.2 6.2.2.0 fail to validate the URL scheme when checking whether a target URL is internal to the connected server, which allows a network-positioned attacker to load a plugin popout window over an insecure connection via a link using a downgraded URL scheme. Mattermost Advisory ID: MMSA-2026-00717
Affected products
- Mattermost Desktop: from 6.2.0 before 6.2.3 — fixed in 6.2.3
How to fix
Upgrade to a fixed version: Mattermost Desktop 6.2.3. Check the vendor advisory for mitigations.
References
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