CVE-2024-45510 is a stored Cross-Site Scripting (XSS) vulnerability affecting Zimbra Collaboration Suite (ZCS) Webmail Modern UI through version 10.0. The vulnerability stems from insufficient sanitization of user-supplied input in specific email message fields, which allows an attacker to embed malicious JavaScript code. When the victim adds the attacker as a contact, the malicious script is stored in the contact list and executed when the victim views it. This stored XSS can be leveraged to perform unauthorized actions such as sending arbitrary emails on behalf of the victim, exfiltrating mailbox contents, altering the victim’s profile picture, and potentially other malicious activities that compromise confidentiality and integrity of the mailbox. The attack requires the attacker to have privileges to send emails and the victim to perform the action of adding the attacker to their contacts, which involves user interaction. The vulnerability is classified under CWE-79 (Improper Neutralization of Input During Web Page Generation). The CVSS v3.1 base score is 6.1, indicating medium severity, with an attack vector of network, low attack complexity, requiring privileges and user interaction, and impacting confidentiality and integrity but not availability. No public exploits or patches are currently available, emphasizing the importance of proactive mitigation. Proper input validation, sanitization, and escaping of all user-controllable fields in the webmail interface are critical to prevent exploitation.

The impact of CVE-2024-45510 on organizations using Zimbra Collaboration Suite can be significant, particularly for those relying heavily on Zimbra for email communications. Successful exploitation allows attackers to execute arbitrary scripts in the context of the victim’s browser, leading to unauthorized email sending which can facilitate phishing or spam campaigns originating from trusted accounts. Mailbox exfiltration compromises sensitive corporate communications and intellectual property, while profile picture alteration can be used for social engineering or reputational damage. Although the attack requires some privileges and user interaction, the scope includes any user who can be tricked into adding a malicious contact, making it a viable vector for targeted attacks within organizations. The confidentiality and integrity of email communications are at risk, potentially leading to data breaches, compliance violations, and erosion of trust. The absence of known exploits in the wild currently limits immediate widespread impact, but the vulnerability’s presence in a widely used collaboration platform makes it a notable risk for enterprises, government agencies, and educational institutions worldwide.

To mitigate CVE-2024-45510, organizations should implement the following specific measures beyond generic advice: 1) Immediately audit and sanitize all user input fields in the Zimbra Webmail Modern UI, especially those related to email message content and contact management, ensuring proper escaping of HTML and JavaScript characters. 2) Apply any available vendor patches or updates as soon as they are released; if patches are not yet available, consider deploying Web Application Firewalls (WAFs) with custom rules to detect and block suspicious script injection patterns targeting Zimbra interfaces. 3) Restrict the ability to add contacts or send emails to trusted users only, and monitor contact list changes for anomalous additions. 4) Educate users about the risks of adding unknown contacts and encourage verification of contact sources. 5) Implement Content Security Policy (CSP) headers to limit the execution of unauthorized scripts within the webmail environment. 6) Conduct regular security assessments and penetration tests focusing on webmail interfaces to detect similar injection flaws. 7) Monitor logs for unusual email sending patterns or access to contact lists that may indicate exploitation attempts.