# CVE-2026-40875

> Vulnerability.

## 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.

## Key facts

- **CVE ID:** CVE-2026-40875
- **Published:** 2026-04-21
- **CWE codes:** CWE-79, CWE-80

## Primary sources

- NIST NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-40875

## Citation

> AI Analytics. CVE-2026-40875. Retrieved 2026-08-02 from https://api.ai-analytics.org/cve/CVE-2026-40875. Derived from NIST NVD. Licensed CC0.

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