CVE-2026-6517

7.7 highEPSS 0.2%

High (7.7) in mattermost mattermost desktop. EPSS 0.2% chance of exploitation in the next 30 days.

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

Severity

CVSS 3.1

7.7 high

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N

EPSS: 0.2% chance of exploitation in the next 30 days; higher than 8% of CVEs (scores of 2026-10-31)
CWE: CWE-522
Published: 2026-06-15
Modified: 2026-06-17
Record from: the NVD, synced 2026-10-19

Affected

mattermost:mattermost_desktop

References

https://mattermost.com/security-updates

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