CVE-2024-4045 in Popup Builder Plugin
Summary
by MITRE • 05/25/2024
The Popup Builder by OptinMonster – WordPress Popups for Optins, Email Newsletters and Lead Generation plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the ‘campaign_id’ parameter in versions up to, and including, 2.16.1 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with contributor-level permissions and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.
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Analysis
by VulDB Data Team • 07/16/2025
The vulnerability identified as CVE-2024-4045 affects the Popup Builder plugin for WordPress, a widely used tool for creating opt-in popups, email newsletters, and lead generation forms. This plugin has been installed on numerous WordPress websites, making it a potential target for malicious actors seeking to exploit weaknesses in web applications. The vulnerability specifically resides within the plugin's handling of the 'campaign_id' parameter, which is processed through user input without proper sanitization measures. The issue impacts versions up to and including 2.16.1, indicating that the developers have not yet released a patch to address this security flaw. The vulnerability classification aligns with CWE-79 which describes improper neutralization of input during web page generation, commonly known as cross-site scripting. This weakness allows attackers to inject malicious scripts that can be executed in the context of other users' browsers, potentially leading to unauthorized actions or data theft.
The technical flaw manifests through insufficient input sanitization and output escaping mechanisms within the plugin's codebase. When an authenticated attacker with contributor-level permissions or higher submits a crafted 'campaign_id' parameter, the system fails to properly validate or sanitize the input before processing it. This lack of input validation creates an environment where malicious scripts can be stored within the application's database or configuration files. The stored scripts are then executed whenever legitimate users access pages containing the injected content, making this a classic case of stored cross-site scripting. The vulnerability operates at the application layer, where the plugin's backend processing does not adequately escape output that originates from user-supplied input, creating a persistent threat that can affect multiple users over time.
The operational impact of this vulnerability extends beyond simple script execution, as it provides attackers with a vector for more sophisticated attacks within the compromised WordPress environment. Contributors and higher-level users typically have the ability to create and modify content, making them ideal candidates for exploitation. Once an attacker successfully injects malicious scripts, they can potentially steal session cookies, redirect users to malicious websites, or even modify content on the site. The threat is particularly concerning because the vulnerability requires only contributor-level access, which is often granted to trusted users who may not be fully aware of the security implications of their actions. This makes the attack surface larger and more difficult to control, as administrators may not immediately detect the presence of malicious code within legitimate user-generated content.
Mitigation strategies for CVE-2024-4045 should focus on immediate remediation and ongoing security monitoring. The most effective immediate solution is to upgrade to a patched version of the Popup Builder plugin, which should include proper input validation and output escaping mechanisms. Organizations should also implement strict access controls, limiting contributor-level permissions to trusted individuals only and regularly reviewing user roles and capabilities. Input sanitization should be implemented at multiple layers, including server-side validation and proper output escaping before any user-supplied data is rendered in web pages. Security monitoring should include regular scans for malicious code within the plugin's configuration files and database entries. Additionally, implementing content security policies can provide an additional layer of protection against script execution, as outlined in the ATT&CK framework under the technique of T1059.001 for command and scripting interpreter. Administrators should also consider implementing web application firewalls to detect and block suspicious requests containing potential XSS payloads, and conduct regular security audits to identify similar vulnerabilities in other installed plugins and themes.