CVE-2024-11182 is an XSS vulnerability classified under CWE-79 affecting MDaemon Email Server versions before 24.5.1c. The flaw arises from improper neutralization of input during web page generation in the webmail interface. Specifically, an attacker can craft an HTML email containing JavaScript embedded in an img tag. When a user views or previews this email in the webmail client, the malicious script executes within the browser context of the victim. This can lead to unauthorized actions such as session hijacking, theft of cookies or credentials, or execution of arbitrary code within the user's browser session. The vulnerability does not require any prior authentication, increasing its risk profile, but does require user interaction to open or preview the malicious email. The CVSS 4.0 vector indicates network attack vector, low attack complexity, no privileges required, user interaction required, and low to limited impact on confidentiality and integrity, with no impact on availability. No public exploit code or active exploitation has been reported to date. The vulnerability highlights the importance of proper input sanitization and output encoding in webmail applications to prevent script injection attacks.

For European organizations, this vulnerability poses a moderate risk primarily to confidentiality and integrity of email communications and user sessions. Successful exploitation could allow attackers to steal session cookies or credentials, enabling unauthorized access to email accounts and potentially sensitive corporate information. This could lead to further lateral movement within networks or data exfiltration. The impact is particularly significant for organizations relying on MDaemon Email Server for critical communications, including government agencies, financial institutions, and enterprises with sensitive data. The requirement for user interaction (opening or previewing the malicious email) means phishing or social engineering campaigns could be used to exploit this vulnerability. While availability impact is minimal, the compromise of email accounts can disrupt business operations and damage trust. The absence of known exploits reduces immediate risk but does not eliminate the threat, especially as attackers often develop exploits rapidly after disclosure.

Organizations should immediately upgrade MDaemon Email Server to version 24.5.1c or later, where this vulnerability is fixed. Until patching is complete, implement strict email content filtering to block or sanitize HTML emails containing potentially malicious tags or scripts. Deploy advanced anti-phishing and anti-spam solutions to detect and quarantine suspicious emails. Configure webmail clients to disable automatic loading or previewing of HTML content where possible, or restrict JavaScript execution in the webmail interface. Educate users about the risks of opening unexpected or suspicious emails, emphasizing caution with HTML content. Monitor email logs and webmail access for unusual activity indicative of exploitation attempts. Consider deploying Content Security Policy (CSP) headers in the webmail application to restrict script execution. Regularly review and update security policies related to email handling and webmail usage to reduce attack surface.