CVE-2026-6517

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

CVSS v3 6.3 MEDIUM

6.3^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 1.8 / Impact : 4.0

Attack Vector NETWORK

Attack Complexity HIGH

Privileges Required LOW

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact NONE

Availability Impact NONE

Scope CHANGED

References

Link	Resource
https://mattermost.com/security-updates	Vendor Advisory

Configurations

Configuration 1 (hide)

OR	cpe:2.3:a:mattermost:mattermost_desktop::-::::::*
	cpe:2.3:a:mattermost:mattermost_desktop::::::::

History

No history.

Information

Published : 2026-06-15 14:16

Updated : 2026-06-17 11:00

NVD link : CVE-2026-6517

Mitre link : CVE-2026-6517

CVE.ORG link : CVE-2026-6517

JSON object : View

Products Affected

mattermost

mattermost_desktop

CWE

CWE-522

Insufficiently Protected Credentials

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