CVE-2026-66711 in Multilingual & Multicurrency Plugin
Summary
by MITRE • 08/06/2026
Subscriber Cross Site Scripting (XSS) in WooCommerce Multilingual & Multicurrency <= 5.5.6 versions.
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Analysis
by VulDB Data Team • 08/06/2026
The vulnerability identified as subscriber cross site scripting in WooCommerce Multilingual & Multicurrency versions up to 5.5.6 represents a critical security flaw that allows attackers to inject malicious scripts into web pages viewed by users. This issue stems from insufficient input validation and output sanitization within the plugin's handling of user-submitted data, particularly affecting the subscription management functionality. The vulnerability falls under CWE-79 which specifically addresses cross site scripting flaws where untrusted data is improperly incorporated into web page content without proper sanitization measures.
The technical implementation of this XSS flaw occurs when subscriber information including email addresses, names, and other personal details are processed by the plugin's backend systems. Attackers can exploit this weakness by crafting malicious payloads that contain script tags or other executable code within subscription forms or user management interfaces. When legitimate users view pages containing the compromised subscriber data, their browsers execute the injected malicious scripts within the context of the vulnerable website, potentially leading to session hijacking, credential theft, or redirection to malicious sites.
The operational impact of this vulnerability extends significantly beyond simple script execution as it compromises the integrity and confidentiality of user data within e-commerce environments. Attackers can leverage this weakness to steal customer sessions, access sensitive subscription information, manipulate order processing, and potentially gain unauthorized access to merchant accounts. The vulnerability affects WooCommerce stores that rely on multilingual and multicurrency features, making it particularly dangerous for international businesses handling multiple currency transactions and diverse language support. This weakness directly impacts the trust model between merchants and customers, potentially causing significant financial and reputational damage.
Mitigation strategies should include immediate patching of the vulnerable plugin to version 5.5.7 or later, which contains proper input validation and output sanitization mechanisms. Security hardening measures must involve implementing strict content security policies, enabling automatic escaping of all user-generated content, and conducting regular security audits of third-party plugins. Organizations should also implement web application firewalls to detect and block suspicious script injection attempts while establishing monitoring protocols for unusual activity patterns in subscription management systems. The vulnerability demonstrates the importance of proper secure coding practices and input validation as outlined in the OWASP Top Ten security framework, particularly addressing the critical need for sanitizing all user inputs before rendering them in web contexts.
Additional protective measures include regular security assessments of e-commerce platforms, maintaining up-to-date plugin repositories, and implementing principle of least privilege access controls for subscription management functions. Organizations should also consider implementing automated vulnerability scanning tools that can identify similar XSS vulnerabilities across their web applications. The ATT&CK framework categorizes this type of vulnerability under the T1059 technique for command and script injection, highlighting how attackers can leverage such weaknesses to establish persistent access and escalate privileges within compromised systems. Regular security training for developers on secure coding practices remains essential in preventing similar vulnerabilities from emerging in future software releases.