CVE-2026-6517
Mattermost Desktop App fails to restrict the allow list of domains which NTLM credentials are passed
- State
- Published
- Severity
- 6.3 Medium
- Published
- Jun 15, 2026
- Updated
- Jun 15, 2026
- Reserved
- Apr 17, 2026
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
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 6.3 Medium | CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N | Mattermost |
Weaknesses
- CWE-522 Insufficiently Protected Credentials
Affected Products
| Product | Versions |
|---|---|
MattermostMattermost |
|
References
- MMSA-2026-00651vendor-advisory
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