CVE-2026-6517
MEDIUM
6,3
Source: [email protected]
Attack Vector: network
Attack Complexity: high
Privileges Required: low
User Interaction: none
Scope: changed
Confidentiality: high
Integrity: none
Availability: none
Description
AI Translation Available
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
522
Insufficiently Protected Credentials
IncompleteCommon Consequences
Security Scopes Affected:
Access Control
Potential Impacts:
Gain Privileges Or Assume Identity
Applicable Platforms
Technologies:
Not Technology-Specific, Web Based, ICS/OT
https://mattermost.com/security-updates