CVE-2024-13403 is a stored Cross-Site Scripting (XSS) vulnerability classified under CWE-79 found in the WPForms – Easy Form Builder for WordPress plugin, which is widely used for creating contact forms, payment forms, surveys, and more. The vulnerability exists in all versions up to and including 1.9.3.1 due to insufficient input sanitization and output escaping of the 'fieldHTML' parameter. Authenticated users with Contributor-level access or higher can exploit this flaw by injecting arbitrary JavaScript code into form fields or other input areas that accept HTML content. Because the malicious script is stored persistently, it executes in the context of any user who views the affected page, potentially compromising user sessions, stealing cookies, or performing unauthorized actions on behalf of users. The vulnerability has a CVSS 3.1 base score of 6.4, reflecting medium severity, with an attack vector of network, low attack complexity, requiring privileges (Contributor or above), no user interaction, and scope change. No public exploits have been reported yet, but the presence of this vulnerability in a popular WordPress plugin makes it a significant risk. The vulnerability highlights the importance of proper input validation and output encoding in web applications, especially those that allow user-generated content. Since WordPress powers a large portion of the web, and WPForms is a popular plugin, the potential attack surface is extensive. The vulnerability affects the confidentiality and integrity of user data but does not impact availability directly.

The impact of CVE-2024-13403 is primarily on the confidentiality and integrity of data within affected WordPress sites. Attackers with Contributor-level access can inject malicious scripts that execute in the browsers of site visitors or administrators, leading to session hijacking, credential theft, defacement, or unauthorized actions performed with the victim's privileges. This can result in data breaches, reputational damage, and potential further compromise of the affected websites. Since the vulnerability requires authenticated access, the risk is somewhat mitigated but remains significant in environments where Contributor or higher roles are assigned to multiple users or where attackers can gain such access through other means. The vulnerability does not directly affect availability but can indirectly cause service disruption if exploited to deface or manipulate site content. Organizations relying on WPForms for critical forms, payment processing, or surveys may face compliance and operational risks if exploited. The widespread use of WordPress and WPForms increases the global risk exposure, especially for sites with multiple contributors or public-facing interactive content.

To mitigate CVE-2024-13403, organizations should first check for and apply any official patches or updates released by the WPForms vendor as soon as they become available. In the absence of patches, administrators should restrict Contributor-level access to trusted users only and review user roles to minimize the number of users with permissions to inject content. Implementing a Web Application Firewall (WAF) with rules to detect and block suspicious script injections targeting the 'fieldHTML' parameter can provide temporary protection. Additionally, site administrators should enable Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts. Regularly auditing and sanitizing existing form content for injected scripts is recommended. Developers maintaining custom integrations with WPForms should ensure proper input validation and output encoding on all user-supplied data. Monitoring logs for unusual activities related to form submissions or user content changes can help detect exploitation attempts early. Finally, educating users with elevated privileges about the risks of XSS and safe content practices can reduce accidental exploitation.