CVE-2025-57891 is a medium severity vulnerability classified as CWE-79, which corresponds to Improper Neutralization of Input During Web Page Generation, commonly known as Cross-site Scripting (XSS). This vulnerability affects the wpecommerce plugin 'Recurring PayPal Donations' up to version 1.8. The issue allows an attacker to inject malicious scripts that are stored persistently on the affected system and executed in the context of users' browsers when they access the vulnerable web pages. Specifically, the vulnerability arises because the plugin does not properly sanitize or neutralize user-supplied input before embedding it into web pages, enabling stored XSS attacks. The CVSS v3.1 base score is 5.9, indicating a medium severity level, with the vector AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:L. This means the attack can be performed remotely over the network with low attack complexity but requires high privileges and user interaction. The scope is changed (S:C), indicating that the vulnerability affects resources beyond the security scope of the vulnerable component. The impact includes limited confidentiality, integrity, and availability losses. No known exploits are currently reported in the wild, and no patches have been linked yet. Stored XSS vulnerabilities can be leveraged by attackers to hijack user sessions, deface websites, redirect users to malicious sites, or deliver malware payloads, posing significant risks especially to administrative users or those with elevated privileges.

For European organizations using the wpecommerce Recurring PayPal Donations plugin, this vulnerability could lead to unauthorized script execution within the browsers of administrators or users interacting with the donation system. This may result in session hijacking, unauthorized actions performed on behalf of legitimate users, theft of sensitive data, or distribution of malware. Given that the vulnerability requires high privileges and user interaction, the risk is somewhat mitigated but still significant in environments where multiple users have elevated access or where phishing campaigns could be used to trick users into triggering the exploit. Non-profit organizations, charities, and other entities relying on this plugin for recurring donations could face reputational damage, financial fraud, or data breaches. Additionally, the cross-site scripting vulnerability could be used as a pivot point for further attacks within the organization's web infrastructure. Compliance with GDPR and other European data protection regulations could be impacted if personal data is compromised due to exploitation of this vulnerability.

1. Immediate mitigation should include restricting access to the affected plugin's administrative interfaces to trusted personnel only and enforcing strict user privilege management to minimize the number of users with high privileges. 2. Implement Web Application Firewall (WAF) rules specifically targeting common XSS attack patterns to provide an additional layer of defense. 3. Conduct thorough input validation and output encoding on all user-supplied data within the plugin codebase, focusing on HTML context encoding to neutralize malicious scripts. 4. Monitor web server and application logs for unusual activity that may indicate attempted exploitation. 5. Since no official patch is currently linked, organizations should engage with the vendor or community to obtain or develop a patch or update to fix the input sanitization flaw. 6. Educate users with elevated privileges about the risks of phishing and social engineering attacks that could trigger the stored XSS. 7. Consider temporarily disabling or replacing the vulnerable plugin with alternative donation management solutions until a secure version is available.