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CVE-2026-6517 | Mondoo Vulnerability Intelligence

Vulnerability IntelligenceCVE-2026-6517

CVE-2026-6517

MEDIUM6.3

Mattermost Desktop App fails to restrict the allow list of domains which NTLM credentials are passed

Published Jun 15, 2026

Modified 1 weeks ago

Details

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

References

https://mattermost.com/security-updates

https://www.cve.org/CVERecord?id=CVE-2026-6517

CVSS Analysis

CVSS v3.1

6.3

Exploitability

Attack Vector

NetworkAV:N

Attack Complexity

HighAC:H

Privileges Required

LowPR:L

User Interaction

NoneUI:N

Scope

Scope

ChangedS:C

Impact

Confidentiality

HighC:H

Integrity

NoneI:N

Availability

NoneA:N

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

Weakness Type (CWE)

Other

Ecosystems

Timeline

PublishedJun 15, 2026

ModifiedJun 15, 2026