Vulnerability · Published Apr 21, 2026 · Assigned by GitHub_M
CVE-2026-40875mailcow: dockerized vulnerable to stored XSS in user login history real_rip
High 7.0
In plain English
A high-severity cross-site scripting in mailcow-dockerized from mailcow. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 15% of all known vulnerabilities).
Official description
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.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| mailcow | mailcow-dockerized | < 2026-03b |
Weakness: CWE-79, CWE-80 · Vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:P/VC:H/VI:N/VA:N/SC:H/SI:H/SA:N