CVE-2026-78172 in Themify Plugin
Summary
by MITRE • 09/11/2026
The Themify – WooCommerce Product Filter plugin for WordPress is vulnerable to Reflected Cross-Site Scripting via Query Parameter Name in all versions up to, and including, 1.5.5 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.
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Analysis
by VulDB Data Team • 09/11/2026
The Themify WooCommerce Product Filter plugin, widely utilized within the WordPress ecosystem to enhance e-commerce functionality by allowing users to filter products based on various attributes, contains a critical security flaw in versions up to and including 1.5.5. This vulnerability is classified as a Reflected Cross-Site Scripting (XSS) issue specifically triggered through query parameter names rather than values or body content. The root cause lies in insufficient input sanitization and output escaping mechanisms within the plugin's codebase. When the application processes HTTP requests, it fails to adequately validate or encode the keys of query parameters before they are reflected back into the HTML response. This architectural oversight allows malicious actors to inject executable JavaScript payloads directly through specially crafted URLs that manipulate these parameter names.
From a technical perspective, this vulnerability aligns with CWE-79, which describes Improper Neutralization of Input During Web Page Generation commonly known as Cross-site Scripting. The attack vector is particularly insidious because it relies on social engineering tactics to achieve execution. An attacker does not need valid credentials or authentication privileges to exploit this flaw. Instead, they construct a malicious URL where the query parameter name contains script tags or event handlers designed to execute arbitrary code in the context of the victim's browser session. When an authenticated user with sufficient permissions clicks on such a link, typically disguised as a legitimate product filter or promotional content, their browser parses and executes the injected scripts. This execution occurs within the security context of the WordPress site, granting the attacker significant leverage over the user's interaction with the application.
The operational impact of this vulnerability is severe due to its potential for session hijacking, credential theft, and defacement. Since the script runs in the victim's browser, it can access cookies containing authentication tokens, potentially allowing an unauthenticated attacker to impersonate a legitimate user or administrator. This could lead to unauthorized changes to product listings, pricing structures, or customer data within the WooCommerce environment. Furthermore, attackers may use this vector to redirect users to phishing sites designed to harvest sensitive information or distribute malware. The reflected nature of the XSS means that each attack requires individual targeting via social engineering, but once successful, it can compromise not only the individual user's session but also potentially expose broader organizational data if administrative privileges are obtained through subsequent exploitation steps.
This vulnerability is closely mapped to MITRE ATT&CK technique T1059.007, which refers to JavaScript execution within a browser environment as part of an initial access or persistence strategy. The lack of proper encoding for query parameter names represents a fundamental failure in input validation protocols that are standard practice in secure web development frameworks. To mitigate this risk immediately, administrators should upgrade the Themify WooCommerce Product Filter plugin to version 1.5.6 or later where these sanitization and escaping issues have been addressed by the developers. In cases where upgrading is not immediately feasible, implementing a Web Application Firewall (WAF) with rules specifically designed to detect and block malicious payloads in URL query strings can provide an additional layer of defense. Additionally, enforcing strict Content Security Policy headers that restrict script execution sources can help mitigate the impact of any successful injection attempts by preventing unauthorized scripts from running even if they are injected into the page DOM.