What’s Vulnerable › Vulnerabilities
CVE-2026-6517: Mattermost Desktop App fails to restrict the allow list of domains which NTLM credentials are passed
- Severity: high (CVSS 7.7 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: 2026-06-15 · updated 2026-06-17
- Weakness: CWE-522
Description
Mattermost Desktop App versions <=6.1 5.5.13.0 fail to restrict the allow list of domains to which NTLM credentials were forwarded to in the Mattermost Desktop App which allows any user on a server without the image proxy enabled to intercept other users credentials via embedding an image that routes to an external web server. Mattermost Advisory ID: MMSA-2026-00651
Affected products
- Mattermost Desktop: through 5.13.0; from 6.1.0 through 6.1.5
References
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