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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.

PUBLISHED Reserved 2026-04-15 | Published 2026-04-21 | Updated 2026-04-21 | Assigner GitHub_M




HIGH: 7.0CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:P/VC:H/VI:N/VA:N/SC:H/SI:H/SA:N

Problem types

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)

Product status

< 2026-03b
affected

References

github.com/...erized/security/advisories/GHSA-jprq-w83q-q62h exploit

github.com/...erized/security/advisories/GHSA-jprq-w83q-q62h

cve.org (CVE-2026-40875)

nvd.nist.gov (CVE-2026-40875)

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