CVE-2026-40878 | mailcow mailcow-dockerized prior 2026-03b Web Interface setLang REQUEST_URI cross site scripting (GHSA-xv9r-j862-5hqf)

VDB-358586 · CVE-2026-40878 · GHSA-XV9R-J862-5HQF MAILCOW MAILCOW-DOCKERIZED PRIOR 2026-03B WEB INTERFACE SETLANG REQUEST_URI CROSS SITE SCRIPTING HISTORYDIFFRELATEJSONXMLCTI CVSS Meta Temp Score Current Exploit Price (≈) CTI Interest Score 4.1 $0-$5k 2.80+ Summaryinfo A vulnerability was found in mailcow mailcow-dockerized and classified as problematic. This affects the function setLang of the component Web Interface. Such manipulation of the argument REQUEST_URI leads to cross site scripting. This vulnerability is documented as CVE-2026-40878. The attack can be executed remotely. There is not any exploit available. It is suggested to upgrade the affected component. Detailsinfo A vulnerability was found in mailcow mailcow-dockerized. It has been rated as problematic. Affected by this issue is the function setLang of the component Web Interface. The manipulation of the argument REQUEST_URI with an unknown input leads to a cross site scripting vulnerability. Using CWE to declare the problem leads to CWE-79. The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. Impacted is integrity. CVE summarizes: mailcow: dockerized is an open source groupware/email suite based on docker. In versions prior to 2026-03b, the mailcow web interface passes the raw `$_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. The advisory is available at github.com. This vulnerability is handled as CVE-2026-40878 since 04/15/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. Successful exploitation requires user interaction by the victim. Technical details are known, but there is no available exploit. This vulnerability is assigned to T1059.007 by the MITRE ATT&CK project. Upgrading to version 2026-03b eliminates this vulnerability. Productinfo Type Virtualization Software Vendor mailcow Name mailcow-dockerized Website Product: https://github.com/mailcow/mailcow-dockerized/ CPE 2.3info 🔒 CPE 2.2info 🔒 CVSSv4info VulDB Vector: 🔒 VulDB Reliability: 🔍 CNA CVSS-B Score: 🔒 CNA CVSS-BT Score: 🔒 CNA Vector: 🔒 CVSSv3info VulDB Meta Base Score: 4.3 VulDB Meta Temp Score: 4.1 VulDB Base Score: 4.3 VulDB Temp Score: 4.1 VulDB Vector: 🔒 VulDB Reliability: 🔍 CVSSv2info Vector Complexity Authentication Confidentiality Integrity Availability Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock VulDB Base Score: 🔒 VulDB Temp Score: 🔒 VulDB Reliability: 🔍 Exploitinginfo Class: Cross site scripting CWE: CWE-79 / CWE-94 / CWE-74 CAPEC: 🔒 ATT&CK: 🔒 Physical: No Local: No Remote: Yes Availability: 🔒 Status: Not defined Price Prediction: 🔍 Current Price Estimation: 🔒 0-Day Unlock Unlock Unlock Unlock Today Unlock Unlock Unlock Unlock Threat Intelligenceinfo Interest: 🔍 Active Actors: 🔍 Active APT Groups: 🔍 Countermeasuresinfo Recommended: Upgrade Status: 🔍 0-Day Time: 🔒 Upgrade: mailcow-dockerized 2026-03b Timelineinfo 04/15/2026 CVE reserved 04/21/2026 +6 days Advisory disclosed 04/21/2026 +0 days VulDB entry created 04/21/2026 +0 days VulDB entry last update Sourcesinfo Product: github.com Advisory: GHSA-xv9r-j862-5hqf Status: Confirmed CVE: CVE-2026-40878 (🔒) GCVE (CVE): GCVE-0-2026-40878 GCVE (VulDB): GCVE-100-358586 scip Labs: https://www.scip.ch/en/?labs.20171019 Entryinfo Created: 04/21/2026 22:35 Changes: 04/21/2026 22:35 (70) Complete: 🔍 Cache ID: 99:665:101 Discussion No comments yet. Languages: en. Please log in to comment. ◂ PreviousOverviewNext ▸