CVE-2024-9528 is a stored Cross-Site Scripting vulnerability identified in the Contact Form Plugin by Fluent Forms for Quiz, Survey, and Drag & Drop WP Form Builder, a popular WordPress plugin developed by techjewel. The vulnerability affects all versions up to and including 5.1.19. It stems from improper neutralization of input during web page generation (CWE-79), specifically in the form label fields where user-supplied input is not properly sanitized or escaped before being rendered on pages. This allows an authenticated attacker with the ability to edit forms—typically an administrator—to inject arbitrary JavaScript code into form labels. When any user visits a page containing the injected form, the malicious script executes in their browser context. This can lead to theft of session cookies, redirection to malicious sites, or other client-side attacks. The vulnerability requires low privileges (authenticated user with form editing rights) and no user interaction to trigger once the malicious payload is stored. The CVSS v3.1 base score is 4.9, reflecting medium severity due to the limited scope of affected users (authenticated admins) and the complexity of exploitation (requires form editing access). No public exploits have been reported yet. The vulnerability highlights the importance of proper input validation and output encoding in web applications, especially in plugins widely used on WordPress sites.

The primary impact of CVE-2024-9528 is the potential for stored XSS attacks on WordPress sites using the vulnerable Fluent Forms plugin. Successful exploitation allows attackers to execute arbitrary JavaScript in the browsers of site visitors, which can lead to session hijacking, defacement, phishing, or distribution of malware. Since exploitation requires authenticated access with form editing privileges, the risk is somewhat mitigated by the need for an attacker to have or compromise admin-level credentials. However, many WordPress sites have multiple administrators or editors, increasing the attack surface. The vulnerability could be leveraged in multi-stage attacks where an attacker first gains low-level access and then escalates privileges to inject malicious scripts. For organizations, this can result in reputational damage, data leakage, and loss of user trust. Given the widespread use of WordPress and the popularity of the Fluent Forms plugin, a large number of websites could be affected globally, especially those that do not regularly update plugins or enforce strict access controls.

To mitigate CVE-2024-9528, organizations should immediately update the Fluent Forms plugin to a version where this vulnerability is patched once available. Until an official patch is released, administrators should restrict form editing privileges to the minimum necessary users and audit existing forms for suspicious or unexpected script content in label fields. Implementing Web Application Firewalls (WAFs) with rules to detect and block common XSS payloads targeting form label inputs can provide temporary protection. Additionally, site administrators should enforce strong authentication mechanisms, including multi-factor authentication (MFA), to reduce the risk of credential compromise. Regular security audits and monitoring for unusual admin activity can help detect exploitation attempts. Developers and site owners should also consider applying custom input validation and output encoding on form fields if feasible. Finally, educating administrators about the risks of XSS and safe plugin management practices is essential.