CVE-2024-11182 is a medium-severity Cross-Site Scripting (XSS) vulnerability affecting MDaemon Email Server versions prior to 24.5.1c. The vulnerability arises from improper neutralization of input during web page generation (CWE-79). Specifically, an attacker can craft an HTML email containing a malicious <img> tag with embedded JavaScript code. When a webmail user views this email through the MDaemon webmail interface, the malicious script executes in the context of the user's browser session. This can lead to unauthorized actions such as session hijacking, cookie theft, or other malicious activities that leverage the user's authenticated session. The vulnerability does not require any authentication or privileges to exploit and only requires user interaction in the form of opening or previewing the malicious email. The CVSS 4.0 base score is 5.3, reflecting network attack vector, low attack complexity, no privileges required, but requiring user interaction and having low impact on confidentiality and integrity, with limited scope. No known exploits are reported in the wild yet. The vulnerability is significant because email servers and webmail interfaces are common attack surfaces, and successful exploitation could compromise user accounts or lead to further internal network compromise if leveraged in a targeted attack.

For European organizations, this vulnerability poses a risk primarily to the confidentiality and integrity of email communications and user sessions. Since MDaemon Email Server is used by various enterprises, small and medium businesses, and some public sector entities in Europe, exploitation could lead to unauthorized access to sensitive emails, credential theft, or phishing campaigns leveraging compromised sessions. This could result in data breaches, loss of intellectual property, or disruption of business communications. Additionally, compromised accounts could be used as pivot points for lateral movement within corporate networks. The impact is heightened in sectors with strict data protection regulations such as GDPR, where unauthorized data exposure can lead to significant legal and financial penalties. The vulnerability's requirement for user interaction (opening a malicious email) means that user awareness and email filtering effectiveness will influence the likelihood of successful exploitation.

Organizations should promptly upgrade MDaemon Email Server to version 24.5.1c or later where this vulnerability is patched. In the absence of immediate patching, administrators should implement strict email filtering to block or quarantine emails containing suspicious HTML content, especially those with embedded scripts or unusual <img> tags. Webmail interfaces should be configured to sanitize or disable HTML rendering where possible. User education campaigns should emphasize caution when opening emails from unknown or untrusted sources. Deploying Content Security Policy (CSP) headers on the webmail interface can help mitigate script execution risks. Additionally, monitoring webmail logs for unusual activity and implementing multi-factor authentication (MFA) can reduce the impact of compromised sessions. Regular security assessments and penetration testing should include checks for XSS vulnerabilities in webmail portals.