CVE-2025-66845 is a reflected Cross-Site Scripting (XSS) vulnerability identified in TechStore version 1.0. The vulnerability exists because the user_name endpoint reflects the id query parameter directly into the HTML response without any output encoding or input sanitization. This improper handling allows an attacker to craft a malicious URL containing JavaScript code within the id parameter. When a victim accesses this URL, the malicious script executes in their browser context, enabling the attacker to perform actions such as stealing session cookies, redirecting users to malicious sites, or performing actions on behalf of the user. Reflected XSS vulnerabilities typically require user interaction, such as clicking a crafted link, but do not require authentication, making them relatively easy to exploit. Although no known exploits have been reported in the wild yet, the vulnerability is publicly disclosed and thus could be targeted by attackers. The lack of a CVSS score indicates that the vulnerability has not yet been fully assessed, but the technical details and typical impact of reflected XSS suggest a significant security risk. The vulnerability affects TechStore version 1.0, a product likely used in e-commerce or retail environments, where user trust and data confidentiality are critical.

For European organizations, this vulnerability could lead to significant security incidents including theft of user credentials, session hijacking, and unauthorized actions performed on behalf of users. This can result in data breaches, loss of customer trust, and potential regulatory penalties under GDPR if personal data is compromised. Public-facing web applications using TechStore 1.0 are particularly vulnerable, as attackers can lure users into clicking malicious links. The impact extends to brand reputation damage and potential financial losses due to fraud or remediation costs. Since the vulnerability allows arbitrary script execution, it can also be leveraged to deliver further malware or conduct phishing attacks. Organizations in sectors with high online customer interaction, such as retail, e-commerce, and financial services, face elevated risks. The absence of known exploits currently provides a window for mitigation before widespread attacks occur.

European organizations should immediately implement strict input validation and output encoding on the user_name endpoint to neutralize malicious scripts in the id query parameter. Employing security libraries or frameworks that automatically handle encoding can reduce human error. If available, apply official patches or updates from TechStore vendors promptly. Additionally, implement Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts in browsers. Conduct thorough security testing, including automated scanning and manual penetration testing, to identify similar vulnerabilities in other endpoints. Educate users and staff about the risks of clicking suspicious links and implement web application firewalls (WAFs) to detect and block malicious requests. Monitoring logs for unusual activity related to the user_name endpoint can help detect exploitation attempts early. Finally, consider upgrading to newer, more secure versions of TechStore if available.