CVE-2026-6517

HIGH EPSS 8.5%

Published Jun 15, 20262w ago · Modified Jun 17, 20261w ago

7.7 CVSS 3.1

High

Published Jun 15, 2026 2w ago

Last Modified Jun 17, 2026 1w ago

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

CVSS Details

Base Score

7.7

Exploitability

3.1

Impact

4.0

Vector string

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

Attack Vector Network

Attack Complexity Low

Privileges Required Low

User Interaction None

Scope Changed

Confidentiality High

Integrity None

Availability None

Threat Intelligence

EPSS Exploit Probability

8.5% percentile

Exploit & Patch Status

No Known Exploit

No Patch Available

Weaknesses 1

CWE-522

Affected Products 2

Vendor	Product	Version	Range
mattermost	mattermost_desktop	*	≤5.13.0
mattermost	mattermost_desktop	*	≥6.1.0 – ≤6.1.5

References 1

mattermost.com https://mattermost.com/security-updates

Vendor Advisory

Remediation

No remediation data recorded yet

Check vendor advisories and the NVD entry for patch availability.