CVE-2026-40875

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

State: Published
Severity: 7.0 High
Published: Apr 21, 2026
Updated: Apr 21, 2026
Reserved: Apr 15, 2026

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.

Scores

CVSS	Score	Vector	Source
4.0	7.0 High	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	GitHub_M

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)

Affected Products

Product	Versions
mailcow-dockerizedmailcow	< 2026-03bAffected

References

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

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