CVE-2026-88942 in Product Filter for WooCommerce by WBW Plugin
Summary
by MITRE • 10/31/2026
The Product Filter for WooCommerce by WBW plugin for WordPress is vulnerable to Reflected Cross-Site Scripting via 'wpf_fid' JSON Parameter in all versions up to, and including, 3.4.6 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that execute if they can successfully trick a user into performing an action such as clicking on a link. The vulnerability persists in versions that received the 3.4.3 patch because absint() was applied only to the getVar() read path, leaving the wpf_fid value read from the JSON-decoded filterSettings payload entirely unsanitized.
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Analysis
by VulDB Data Team • 10/31/2026
The Product Filter for WooCommerce plugin by WBW is a widely used extension that enhances product browsing capabilities on WordPress sites powered by WooCommerce. In versions up to and including 3.4.6, this plugin contains a critical security flaw classified as Reflected Cross-Site Scripting (XSS). This vulnerability stems from insufficient input sanitization and output escaping mechanisms when handling the wpf_fid parameter within JSON payloads. The core issue lies in how the application processes filter settings submitted by users or attackers via AJAX requests. Specifically, while earlier patches attempted to address security concerns by applying absint() for integer validation on certain read paths using getVar(), this fix was incomplete and did not cover all execution flows. Consequently, the wpf_fid value extracted from a JSON-decoded filterSettings payload remains entirely unsanitized before being reflected back into the response or used in subsequent operations that may render user-controlled data without proper encoding.
From a technical perspective, the vulnerability allows unauthenticated attackers to inject arbitrary JavaScript code into web pages served by vulnerable instances of the plugin. Because the input is not properly sanitized upon receipt nor escaped prior to output, any script embedded within the wpf_fid parameter will be executed in the context of the victim's browser session when they interact with a maliciously crafted link or form submission directed at the affected endpoint. This reflects directly into the HTTP response, meaning that if an attacker can trick a user into clicking a specially constructed URL containing malicious JavaScript payloads, those scripts will run immediately within the trusted domain of the target website. The lack of authentication requirement makes this vulnerability particularly dangerous as it does not require any prior login or privilege escalation to exploit.
The operational impact of this reflected XSS flaw is significant for both site administrators and end-users. Attackers can leverage this weakness to steal session cookies, hijack user sessions, perform actions on behalf of authenticated users such as modifying product listings or checkout processes, deface websites by injecting malicious content into the page structure, or redirect victims to phishing sites designed to harvest credentials. Since WooCommerce handles sensitive e-commerce data including payment information and personal details, successful exploitation could lead to severe financial loss for merchants and compromise customer privacy. Furthermore, because modern browsers often execute scripts embedded in reflected XSS vectors without additional user interaction beyond clicking a link, the window of opportunity for attackers is wide and the attack vector remains highly effective against typical web users who may not recognize suspicious URLs.
This vulnerability aligns with CWE-79, which describes Improper Neutralization of Input During Web Page Generation commonly known as Cross-site Scripting. It also maps to MITRE ATT&CK technique T1059.007, indicating JavaScript-based command execution through browser-side scripting languages. The failure to sanitize input at the point of ingestion and escape output before rendering represents a classic violation of secure coding principles where trust boundaries are not properly enforced between user-supplied data and application logic. Developers must ensure that all dynamic content derived from external sources undergoes rigorous validation against expected formats and is encoded appropriately for its context, whether HTML, JavaScript, or URL encoding depending on how the value will be utilized within the page structure.
To mitigate this risk, immediate action should be taken by administrators of WordPress sites running affected versions of the Product Filter plugin. The primary remediation step involves upgrading to a patched version where developers have implemented comprehensive input validation and output escaping for all code paths involving user-supplied data such as wpf_fid. Until an update is available or if patching is not immediately feasible, site owners should consider disabling AJAX-based filtering features that expose the vulnerable endpoint temporarily while monitoring access logs for signs of exploitation attempts. Additionally implementing a Web Application Firewall with rules capable of detecting and blocking common XSS payloads in JSON parameters can provide an additional layer of defense against automated attacks targeting this specific weakness. Regular security audits and adherence to OWASP guidelines for input validation and output encoding are essential practices to prevent similar vulnerabilities from being introduced or persisting within web applications over time.