CVE-2025-46499 is a Stored Cross-site Scripting (XSS) vulnerability classified under CWE-79, affecting the hccoder PayPal Express Checkout plugin up to version 2.1.2. This vulnerability arises due to improper neutralization of user-supplied input during web page generation, allowing malicious scripts to be stored and subsequently executed in the context of users visiting affected web pages. Stored XSS differs from reflected XSS in that the malicious payload is permanently stored on the target server, for example within database fields or other persistent storage, and served to users without proper sanitization or encoding. In this case, the vulnerability resides in the PayPal Express Checkout integration provided by hccoder, which is commonly used to facilitate payment processing on e-commerce websites. Exploitation could allow an attacker to inject arbitrary JavaScript code that executes in the browsers of users interacting with the vulnerable checkout pages. This can lead to session hijacking, credential theft, unauthorized actions on behalf of users, or distribution of malware. The vulnerability does not currently have any known exploits in the wild, and no official patches have been published as of the date of disclosure (April 24, 2025). The lack of a CVSS score limits quantitative severity assessment, but the nature of stored XSS vulnerabilities typically poses significant risks to confidentiality and integrity of user data. The vulnerability requires no authentication or user interaction beyond visiting a compromised page, increasing its attack surface. The affected product is a third-party plugin used in web environments that integrate PayPal Express Checkout functionality, which is widely adopted in various e-commerce platforms globally.

For European organizations, this vulnerability poses a moderate to high risk, particularly for online retailers and service providers relying on the hccoder PayPal Express Checkout plugin. Exploitation could lead to theft of customer credentials, session tokens, or payment information, undermining customer trust and potentially causing financial losses. Additionally, attackers could perform unauthorized transactions or manipulate user sessions, leading to fraud or reputational damage. Given the GDPR regulatory environment in Europe, any compromise involving personal data could result in significant compliance penalties and legal consequences. The stored nature of the XSS increases the likelihood of widespread impact as malicious scripts persist and affect multiple users over time. Furthermore, organizations may face indirect impacts such as increased support costs, customer churn, and damage to brand reputation. The absence of known exploits provides a window for proactive mitigation, but the medium severity rating suggests that organizations should prioritize addressing this vulnerability to prevent exploitation.

1. Immediate code review and sanitization: Organizations using the hccoder PayPal Express Checkout plugin should audit all user input fields and ensure proper input validation and output encoding, particularly for HTML and JavaScript contexts. 2. Apply or develop patches: Since no official patch is currently available, organizations should monitor vendor communications for updates or consider implementing custom fixes to neutralize input before rendering. 3. Implement Content Security Policy (CSP): Deploy strict CSP headers to restrict the execution of unauthorized scripts and reduce the impact of potential XSS payloads. 4. Use Web Application Firewalls (WAF): Configure WAF rules to detect and block common XSS attack patterns targeting the affected endpoints. 5. Conduct regular security testing: Perform penetration testing and code scanning focused on XSS vulnerabilities in payment processing components. 6. Educate developers and administrators: Ensure teams understand secure coding practices related to input handling and output encoding. 7. Monitor logs and user reports: Actively monitor for suspicious activity or user complaints that may indicate exploitation attempts. 8. Consider alternative payment plugins: If remediation is delayed, evaluate switching to more secure, actively maintained PayPal integration solutions.