CVE-2026-40875 Details
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.
A stored cross-site scripting vulnerability has been identified in mailcow: dockerized versions prior to 2026-03b. The issue arises in the user dashboard's 'Seen successful connections' login history, which displays client IPs from login logs without proper HTML escaping. This flaw allows an attacker to inject HTML or JavaScript into the 'X-Real-IP' header, which is trusted by the server for logging. Exploitation of this vulnerability can be achieved through a login Cross-Site Request Forgery (CSRF) attack, forcing a victim to log into the attacker's account and then accessing sensitive information, such as emails, in a separate browser tab.
Users are advised to update to mailcow: dockerized version 2026-03b or later, where this vulnerability has been patched.
Metrics
CVSS 4.0 Severity and Vector Strings:
VolerionCVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
Volerion
Assessed Apr 21, 2026CISA-ADP
Assessed Apr 21, 2026References to Advisories, Solutions, and Tools
By selecting these links, you will be leaving this site. These are references gathered from the official CVE record and are not endorsed by Volerion.
| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/mailcow/mailcow-dockerized/security/advisories/GHSA-jprq-w83q-q62h | CISA-ADP | AdvisoryExploitRemedyVendor |
| https://github.com/mailcow/mailcow-dockerized/security/advisories/GHSA-jprq-w83q-q62h | [email protected] | AdvisoryExploitRemedyVendor |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-79 | Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') | [email protected] |
| CWE-80 | Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS) | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| mailcow: dockerized | < 2026-03b |
CPE
Remediation
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Change History
4 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jun 17, 2026 | CVE Modified | [email protected] |
| Jun 17, 2026 | CVE Modified | CISA-ADP |
| Apr 21, 2026 | CVE Modified | CISA-ADP |
| Apr 21, 2026 | New CVE Received | [email protected] |