CVE-2024-11182 is a cross-site scripting (XSS) vulnerability classified under CWE-79 affecting MDaemon Email Server versions before 24.5.1c. The vulnerability arises from improper neutralization of input during web page generation in the webmail interface. Specifically, an attacker can craft an HTML email message embedding JavaScript code within an img tag. When a webmail user views or previews this email, the malicious JavaScript executes in the context of the user's browser session. This can allow the attacker to perform actions such as session hijacking, cookie theft, or executing arbitrary scripts that could manipulate the webmail interface or exfiltrate data. The vulnerability does not require any authentication or elevated privileges to exploit, but it does require user interaction in the form of opening or previewing the malicious email. The CVSS 4.0 base score is 5.3 (medium severity), reflecting network attack vector, low complexity, no privileges required, but requiring user interaction and limited impact on confidentiality and integrity. No known exploits have been reported in the wild as of the publication date. The vulnerability affects the webmail component of MDaemon Email Server, a widely used mail server solution in small to medium enterprises. The root cause is insufficient input sanitization of HTML content in emails, allowing script injection. Remediation involves upgrading to version 24.5.1c or later where the issue is fixed. Additional mitigations include implementing strict email content filtering, disabling HTML email rendering in webmail, and employing Content Security Policy (CSP) headers to restrict script execution.

The primary impact of CVE-2024-11182 is on the confidentiality and integrity of webmail users' sessions and data. Successful exploitation can lead to session hijacking, credential theft, or unauthorized actions performed on behalf of the user within the webmail interface. This can result in unauthorized access to sensitive emails, exposure of private information, or further compromise of the organization's internal network if attackers leverage stolen credentials. The availability impact is minimal as the attack does not directly disrupt service. However, the reputational damage and potential data breaches stemming from this vulnerability can be significant. Organizations relying on MDaemon Email Server for critical communications, especially those with webmail access exposed to the internet, face increased risk. The ease of exploitation (no authentication required, low complexity) combined with user interaction means phishing campaigns could effectively leverage this vulnerability. Although no active exploits are known, the medium severity score indicates a meaningful risk that should be addressed promptly to prevent potential targeted attacks or opportunistic exploitation.

1. Immediately upgrade MDaemon Email Server to version 24.5.1c or later where the vulnerability is patched. 2. Implement strict email filtering rules to block or sanitize incoming emails containing suspicious HTML or JavaScript content, especially those with embedded img tags containing scripts. 3. Configure the webmail interface to disable automatic rendering of HTML emails or restrict it to trusted senders only. 4. Deploy Content Security Policy (CSP) headers on the webmail server to restrict execution of inline scripts and loading of untrusted resources. 5. Educate users about the risks of opening emails from unknown or untrusted sources and encourage cautious handling of unexpected HTML emails. 6. Monitor email server logs and webmail access patterns for unusual activity indicative of exploitation attempts. 7. Consider implementing multi-factor authentication (MFA) for webmail access to reduce impact if credentials are compromised. 8. Regularly review and update security policies related to email handling and webmail usage to incorporate lessons learned from this vulnerability.