CVE-2024-29820 in PDF Builder for WPForms Plugin
Summary
by MITRE • 03/27/2024
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in RedNao PDF Builder for WPForms allows Stored XSS.This issue affects PDF Builder for WPForms: from n/a through 1.2.88.
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Analysis
by VulDB Data Team • 04/12/2025
The vulnerability identified as CVE-2024-29820 represents a critical cross-site scripting flaw within the RedNao PDF Builder plugin for WPForms, specifically impacting versions ranging from the initial release through 1.2.88. This weakness resides in the improper neutralization of input during web page generation processes, creating an environment where malicious scripts can be persistently stored and subsequently executed within the context of affected user browsers. The vulnerability manifests as a stored XSS attack vector, meaning that once malicious input is submitted and processed by the plugin, it remains embedded within the application's data storage and can be served to other users without additional interaction from the attacker.
The technical implementation of this vulnerability stems from inadequate sanitization and validation of user-supplied input within the PDF generation workflow. When users create or modify PDF forms through the WPForms interface, the plugin processes various input fields including form field names, labels, and content that gets rendered into PDF documents. The flaw occurs when these inputs are not properly escaped or validated before being stored and later retrieved for display, allowing attackers to inject malicious JavaScript code that executes in the browsers of unsuspecting users who view the affected PDFs or interact with the form interface. This represents a classic stored XSS vulnerability classified under CWE-79, which specifically addresses improper neutralization of input during web page generation processes.
The operational impact of this vulnerability extends beyond simple script execution, creating significant security risks for organizations relying on WPForms and PDF Builder for their document generation needs. Attackers can leverage this vulnerability to steal session cookies, perform unauthorized actions on behalf of users, redirect victims to malicious sites, or even escalate privileges within the WordPress environment. The persistence of the attack vector means that once the malicious payload is injected, it continues to affect users until the vulnerability is patched or the malicious content is manually removed from the system. This makes the vulnerability particularly dangerous in multi-user environments where administrators may not immediately detect the presence of malicious code within the PDF generation workflow.
Mitigation strategies for CVE-2024-29820 should prioritize immediate patching of the affected plugin to version 1.2.89 or later, as this represents the most effective defense against the stored XSS vulnerability. Organizations should also implement comprehensive input validation and output encoding mechanisms within their WordPress environments, ensuring that all user-supplied content undergoes proper sanitization before being processed or stored. Network-based solutions such as web application firewalls can provide additional layers of protection by monitoring for suspicious script patterns in HTTP requests and blocking known malicious payloads. Security monitoring should be enhanced to detect unusual activity patterns that might indicate exploitation attempts, and regular security audits should verify that no malicious content has been injected into the system. The vulnerability's classification under ATT&CK technique T1566.001 for "Phishing with Social Engineering" underscores the potential for attackers to use this flaw as part of broader social engineering campaigns, making comprehensive security awareness training essential for all users who interact with the affected plugin.