CVE-2026-6517CWE-522

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

Medium · published June 15, 2026

CVSS v3.1
6.3
EPSS
0%
Percentile
23.3
In the wild
Unconfirmed
What it is

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

The record
Technical detail
CVSS v3.1
6.3 · MEDIUM
Vector
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N
CVSS v4.0
Not supplied
EPSS
0.00316 · 23.3th percentile
Weakness
CWE-522 · Insufficiently Protected Credentials
Published
2026-06-15T13:55Z
EPSS history
Timeline
  • 15 JUN 13:55Z
    Mattermost Desktop App fails to restrict the allow list of domains which NTLM credentials are passed
    cvelistv5