CVE-2026-75588

Mattermost Desktop App versions <=6.2 6.2.2.0 fail to validate the URL scheme when checking whether a target URL is internal to the connected server, which allows a network-positioned attacker to load a plugin popout window over an insecure connection via a link using a downgraded URL scheme. Mattermost Advisory ID: MMSA-2026-00717

Score

CVSS 3.1 2.6 Low

Status

Analyzed - responsibledisclosure@mattermost.com

Published

2026-09-17

Last modified

2026-10-13

Weaknesses

CWE-1287

Affected products

• Mattermost (Mattermost)
• Mattermost Desktop (Mattermost)

References

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