CVE-2026-40875

mailcow: dockerized is an open source groupware/email suite based on docker. In versions prior to 2026-03b, the user dashboard's "Seen successful connections" (login history) renders the client IP from login logs without HTML escaping. Because the server trusts the X-Real-IP header as the source IP for logging, an attacker can inject HTML/JS into this field. This Self-XSS can be exploited by a Login CSRF to force the victim into the attacker's account, and then read emails in a previous browser tab. Version 2026-03b fixes the vulnerability.

• CWE-79
• CWE-80

• https://github.com/mailcow/mailcow-dockerized/security/advisories/GHSA-jprq-w83q-q62h
• https://github.com/mailcow/mailcow-dockerized/security/advisories/GHSA-jprq-w83q-q62h

Published

Apr 21, 2026

Last Modified

Jun 17, 2026

Status

Deferred

• How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
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