CVE-2021-24933 in Dynamic Widgets Plugin
Summary
by MITRE • 02/28/2022
The Dynamic Widgets WordPress plugin through 1.5.16 does not escape the prefix parameter before outputting it back in an attribute when using the term_tree AJAX action (available to any authenticated users), leading to a Reflected Cross-Site Scripting issue
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Analysis
by VulDB Data Team • 03/03/2022
The CVE-2021-24933 vulnerability resides within the Dynamic Widgets WordPress plugin version 1.5.16 and earlier, representing a critical reflected cross-site scripting flaw that exploits improper input sanitization mechanisms. This vulnerability specifically manifests when the plugin processes the term_tree AJAX action, which is accessible to any authenticated user within the WordPress environment, thereby expanding the potential attack surface significantly. The flaw occurs because the plugin fails to properly escape the prefix parameter before incorporating it into HTML attributes during the AJAX response generation process. This oversight creates a direct pathway for malicious actors to inject arbitrary JavaScript code that executes in the context of the victim's browser, potentially compromising user sessions and enabling further exploitation.
The technical nature of this vulnerability aligns with CWE-79, which categorizes cross-site scripting flaws as weaknesses in web applications that allow attackers to inject client-side scripts into web pages viewed by other users. The vulnerability operates through a reflected XSS pattern where malicious input is immediately reflected back in the application's response without proper sanitization or encoding. The term_tree AJAX endpoint serves as the attack vector, accepting user-provided prefix parameters that should be treated as untrusted input. When these parameters are directly embedded into HTML attributes without proper HTML escaping, they become susceptible to script injection attacks. The authenticated access requirement does not mitigate the risk significantly since WordPress administrators often maintain persistent sessions, making the exploitation particularly dangerous in environments where administrative privileges are compromised.
The operational impact of this vulnerability extends beyond simple script execution, as it provides attackers with a foothold for more sophisticated attacks within the WordPress ecosystem. An authenticated user with access to the term_tree AJAX action can craft malicious payloads that, when executed, could steal session cookies, redirect users to malicious sites, or perform unauthorized actions within the WordPress administration interface. The reflected nature of the vulnerability means that attackers can deliver payloads through phishing emails or compromised websites, making the attack vector particularly insidious. The vulnerability affects any WordPress installation running the vulnerable Dynamic Widgets plugin version, potentially exposing thousands of websites to this specific threat. Given that the vulnerability is present in the AJAX response handling, it can be exploited even in environments where standard web application firewalls might not detect the malicious traffic due to the legitimate nature of the AJAX endpoint.
Mitigation strategies for CVE-2021-24933 should prioritize immediate plugin updates to versions that address the specific escaping issue in the prefix parameter handling. Organizations should implement comprehensive input validation and output encoding measures, ensuring that all user-provided parameters are properly sanitized before being incorporated into HTML attributes. The implementation of Content Security Policy headers can provide additional defense-in-depth measures, preventing the execution of unauthorized scripts even if the XSS vulnerability is exploited. Security monitoring should focus on detecting unusual AJAX requests to the term_tree endpoint, particularly those containing suspicious script payloads. Regular security audits of WordPress plugins and themes should include checks for proper input sanitization and output escaping practices, aligning with ATT&CK technique T1566 for credential access through web application attacks. The vulnerability demonstrates the importance of proper parameter validation in AJAX endpoints and the critical need for secure coding practices that prevent reflected XSS in web applications, particularly those with authenticated user access.