CVE-2026-40875CWE-79CWE-80

mailcow: dockerized vulnerable to stored XSS in user login history real_rip

High · published April 21, 2026

CVSS v4.0
7.0
EPSS
0%
Percentile
20.5
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v4.0
7.0 · HIGH
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
EPSS
0.00291 · 20.5th percentile
Weaknesses
CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting'); CWE-80 · Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS)
Published
2026-04-21T19:19Z
EPSS history
Timeline
  • 21 APR 19:19Z
    mailcow: dockerized vulnerable to stored XSS in user login history real_rip
    cvelistv5