CVE-2024-6518 is a stored cross-site scripting vulnerability classified under CWE-79, found in the Contact Form Plugin by Fluent Forms for Quiz, Survey, and Drag & Drop WP Form Builder for WordPress. This vulnerability exists in all versions up to and including 5.1.19 due to insufficient sanitization of user input and inadequate output escaping during web page generation. An attacker with Administrator-level access or higher can exploit this flaw by injecting arbitrary JavaScript code into form fields or other input vectors handled by the plugin. Because the malicious script is stored persistently, it executes whenever any user visits the affected page, potentially compromising user sessions, stealing cookies, or performing actions on behalf of users. The vulnerability requires no user interaction but does require high privileges, limiting exploitation to insiders or compromised admin accounts. The CVSS 3.1 score of 5.5 reflects a medium severity with network attack vector, low attack complexity, and no user interaction needed. Although no known exploits are currently in the wild, the vulnerability poses a significant risk to WordPress sites using this plugin, especially those with multiple administrators or high traffic. The absence of official patches at the time of disclosure necessitates immediate mitigation steps to reduce risk.

The primary impact of CVE-2024-6518 is the compromise of confidentiality and integrity within affected WordPress sites. Successful exploitation allows attackers to execute arbitrary scripts in the context of the website, potentially leading to session hijacking, theft of sensitive user data, defacement, or the deployment of further malware. Since the vulnerability requires Administrator-level access, the risk is heightened if an attacker has already gained partial control or insider access. This can facilitate lateral movement or privilege escalation within the organization’s web infrastructure. The stored nature of the XSS means all users visiting the infected pages are at risk, increasing the attack surface. For organizations relying on this plugin for customer interaction, surveys, or forms, the vulnerability could undermine user trust and lead to reputational damage. Additionally, attackers might leverage this vulnerability to bypass security controls or inject malicious payloads that persist beyond a single session. The medium CVSS score reflects moderate impact, but the real-world consequences depend on the attacker’s capabilities and the site’s user base.

To mitigate CVE-2024-6518, organizations should first verify if they use the affected plugin versions and upgrade to a patched release once available. In the absence of an official patch, administrators should restrict plugin access strictly to trusted personnel and consider disabling or removing the plugin temporarily. Implementing a Web Application Firewall (WAF) with custom rules to detect and block suspicious input patterns targeting the plugin’s form fields can reduce exploitation risk. Conduct thorough audits of administrator accounts to ensure no unauthorized access exists and enforce strong authentication mechanisms such as multi-factor authentication (MFA). Additionally, sanitize and validate all user inputs at both client and server sides, and apply output encoding to prevent script execution. Monitoring logs for unusual activity related to form submissions or admin actions can help detect exploitation attempts early. Finally, educate administrators about the risks of stored XSS and the importance of applying security updates promptly.