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CVE-2026-6517 Details

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

Metrics

CVSS 3.x Severity and Vector Strings:

NIST: [email protected]CVSS-B:7.7 HIGHVector:CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N

CNA: [email protected]CVSS-B:6.3 MEDIUMVector:CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N

References to Advisories, Solutions, and Tools

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URL	Source(s)	Tag(s)
https://mattermost.com/security-updates	[email protected]	Vendor Advisory

Weakness Enumeration

CWE-ID	CWE Name	Source
CWE-522	Insufficiently Protected Credentials	[email protected]

Affected Products

Product	Versions
mattermost mattermost desktop	<= 5.13.0 >= 6.1.0, <= 6.1.5
CPE cpe:2.3:a:mattermost:mattermost_desktop::-::::::* cpe:2.3:a:mattermost:mattermost_desktop:::::::: Remediation No remediation found in references.

Change History

4 change records found show changes

Date	Action	Recorded By
Jun 17, 2026	CVE Modified	[email protected]
Jun 17, 2026	CVE Modified	CISA-ADP
Jun 16, 2026	Initial Analysis	[email protected]
Jun 15, 2026	New CVE Received	[email protected]