CVE-2026-6517
Mattermost Desktop App fails to restrict the allow list of domains which NTLM credentials are passed
CVSS Score
6.3
EPSS Score
0.0%
EPSS Percentile
0th
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
| CWE | CWE-522 |
| Vendor | mattermost |
| Product | mattermost |
| Published | Jun 15, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N Attack Vector
Network
Attack Complexity
High
Privileges Required
Low
User Interaction
None
Scope
Changed
Confidentiality
High
Integrity
None
Availability
None
Affected Versions
Mattermost / Mattermost
0 ≤ 5.5.13
Credits
falke