CVE-2021-24432 in Advanced AJAX Product Filters Plugin
Summary
by MITRE • 01/16/2024
The Advanced AJAX Product Filters WordPress plugin does not sanitise the 'term_id' POST parameter before outputting it in the page, leading to reflected Cross-Site Scripting issue.
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Analysis
by VulDB Data Team • 06/11/2025
The Advanced AJAX Product Filters WordPress plugin vulnerability CVE-2021-24432 represents a critical security flaw that exposes WordPress sites to reflected cross-site scripting attacks. This vulnerability specifically affects the plugin's handling of user input within the term_id POST parameter, creating an avenue for malicious actors to inject harmful scripts into web pages viewed by other users. The flaw exists in the plugin's failure to properly sanitize and validate user-supplied data before incorporating it into dynamic web content, making it particularly dangerous in environments where the plugin is actively used for product filtering operations. The vulnerability demonstrates a classic lack of input validation and output sanitization that has been consistently identified as a primary cause of XSS attacks across web applications.
The technical implementation of this vulnerability stems from the plugin's improper handling of the term_id parameter during POST requests. When users interact with the AJAX filtering functionality, the plugin processes the term_id value without applying adequate sanitization measures before rendering it in the HTML output. This allows attackers to craft malicious payloads that get executed in the context of other users' browsers when they view pages containing the filtered results. The reflected nature of this XSS means that the malicious script is not stored on the server but is instead reflected back to users through the vulnerable parameter, making it particularly challenging to detect and prevent. This vulnerability aligns with CWE-79 which specifically addresses cross-site scripting flaws in web applications, and follows the common pattern of insufficient input sanitization leading to code execution in client browsers.
The operational impact of CVE-2021-24432 extends beyond simple script injection, potentially enabling attackers to perform session hijacking, deface websites, steal user credentials, or redirect victims to malicious domains. In WordPress environments, this vulnerability can be exploited to compromise the entire site's security posture, especially when combined with other vulnerabilities or when the affected plugin is used in conjunction with user authentication mechanisms. The reflected nature of the attack means that exploitation requires social engineering to convince users to click on malicious links, but once triggered, the attack can persist across multiple user sessions. Attackers may leverage this vulnerability to escalate privileges, access administrative interfaces, or gain unauthorized control over the affected WordPress installation. The vulnerability affects any WordPress site running the Advanced AJAX Product Filters plugin version prior to the patch, making it a widespread concern for site administrators who have not updated their installations.
Mitigation strategies for CVE-2021-24432 should prioritize immediate plugin updates to the latest secure versions that implement proper input sanitization and output encoding. Site administrators must ensure that all WordPress plugins are kept current with the latest security patches and that regular security audits are conducted to identify vulnerable components. The recommended approach includes implementing Content Security Policy headers to limit script execution, deploying web application firewalls to detect and block malicious payloads, and conducting thorough input validation on all user-supplied parameters. Additionally, administrators should consider implementing proper output encoding mechanisms that prevent script execution in contexts where user input is rendered, following the principle of least privilege and ensuring that all user-facing data is properly escaped before presentation. This vulnerability serves as a reminder of the critical importance of input validation and output sanitization practices that align with established security frameworks and industry standards.