CVE-2025-50848 is a file upload vulnerability identified in CS Cart version 4.18.3, an e-commerce platform widely used for online store management. The vulnerability arises because the application permits unrestricted uploading of HTML files without proper validation or sanitization. When such malicious HTML files are uploaded, they are served directly from the trusted domain and rendered in users' browsers. This behavior enables attackers to craft HTML files containing malicious content, such as fake login forms designed to harvest user credentials or embedded scripts that execute Cross-Site Scripting (XSS) attacks. Since the malicious content originates from the legitimate domain, it bypasses many browser security restrictions and increases the likelihood of successful phishing and script execution attacks against other users of the platform. The vulnerability does not require authentication to exploit, and no user interaction is needed beyond accessing the malicious HTML file. Although no known exploits are currently reported in the wild, the potential for abuse is significant given the nature of the vulnerability and the trust users place in the domain hosting the content. The lack of a CVSS score indicates that the vulnerability is newly published and has not yet been fully assessed for severity.

For European organizations using CS Cart 4.18.3, this vulnerability poses a substantial risk to both the confidentiality and integrity of user data and the availability of the e-commerce platform. Attackers can leverage the vulnerability to conduct phishing campaigns by hosting fake login pages that steal customer credentials, leading to account takeovers and financial fraud. The embedded XSS scripts can also be used to hijack user sessions, deface websites, or distribute malware, damaging brand reputation and customer trust. Furthermore, successful exploitation could lead to regulatory compliance issues under GDPR, as compromised customer data and unauthorized access incidents must be reported and can result in heavy fines. The direct rendering of malicious HTML from a trusted domain increases the attack's effectiveness, making it harder for users to detect phishing attempts. This vulnerability could disrupt business operations, cause financial losses, and erode consumer confidence in affected European e-commerce businesses.

European organizations should immediately implement strict file upload validation controls within their CS Cart installations. This includes restricting allowed file types to safe formats (e.g., images only) and explicitly blocking HTML and other executable content uploads. Employ server-side content scanning and sanitization to detect and remove malicious code before files are stored or served. Additionally, configure web server settings to prevent execution or rendering of uploaded HTML files, such as serving them with Content-Type headers that force download rather than rendering or isolating uploads in separate domains or subdomains with strict Content Security Policies (CSP). Regularly update CS Cart to the latest patched versions once available and monitor vendor advisories for security patches addressing this vulnerability. Implement multi-factor authentication (MFA) for administrative access to reduce the risk of unauthorized uploads. Finally, educate users and administrators about phishing risks and encourage vigilance when interacting with login forms and other sensitive inputs on the platform.