# CVE-2026-40878

> Vulnerability.

## Description

mailcow: dockerized is an open source groupware/email suite based on docker. In versions prior to 2026-03b, the mailcow web interface passes the raw `$_SERVER['REQUEST_URI']` to Twig as a global template variable and renders it inside a JavaScript string literal in the `setLang()` helper of `base.twig`, relying on Twig's default HTML auto-escaping instead of the context-appropriate `js` escaping strategy. In addition, the `query_string()` Twig helper merges all current `$_GET` parameters into the language-switching links on the login page, so attacker-supplied parameters are reflected and preserved across navigation. Version 2026-03b fixes the vulnerability.

## Key facts

- **CVE ID:** CVE-2026-40878
- **Published:** 2026-04-21
- **CWE codes:** CWE-79

## Primary sources

- NIST NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-40878

## Citation

> AI Analytics. CVE-2026-40878. Retrieved 2026-08-08 from https://api.ai-analytics.org/cve/CVE-2026-40878. Derived from NIST NVD. Licensed CC0.

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