CVE-2021-38330 is a Reflected Cross-Site Scripting (XSS) vulnerability identified in the Yet Another bol.com Plugin for WordPress, specifically affecting version 1.4 and earlier. The vulnerability arises from improper handling of the $_SERVER["PHP_SELF"] variable within the ~/yabp.php file. This variable, which contains the current script's filename, is reflected back to the user without adequate sanitization or encoding. An attacker can craft a malicious URL that injects arbitrary JavaScript code into this parameter, which is then executed in the context of the victim's browser when they access the vulnerable page. This reflected XSS flaw allows attackers to perform actions such as session hijacking, defacement, or redirecting users to malicious sites. The vulnerability does not require authentication but does require user interaction, as the victim must click on or visit a crafted URL. The CVSS v3.1 base score is 6.1, indicating a medium severity level, with an attack vector of network (remote), low attack complexity, no privileges required, user interaction required, and a scope change due to the potential impact on other components. The impact affects confidentiality and integrity but not availability. There are no known exploits in the wild, and no official patches have been linked, suggesting that users should apply manual mitigations or updates if available. The plugin is designed to integrate bol.com marketplace features into WordPress sites, primarily targeting e-commerce or affiliate marketing websites that rely on bol.com product listings and sales integration.

For European organizations, particularly those operating e-commerce or affiliate marketing websites using WordPress with the Yet Another bol.com Plugin, this vulnerability poses a risk of client-side attacks that can compromise user trust and data confidentiality. Exploitation could lead to theft of session cookies, enabling attackers to impersonate users or administrators, potentially leading to unauthorized actions within the website. Additionally, attackers could inject malicious scripts to perform phishing attacks or redirect users to fraudulent sites, damaging brand reputation and customer trust. While the vulnerability does not directly affect server availability or integrity, the indirect consequences of compromised user sessions and data leakage can have significant operational and legal repercussions, especially under GDPR regulations. Organizations relying on this plugin without timely updates or mitigations may face increased risk of targeted attacks, particularly in markets where bol.com integration is prevalent.

1. Immediate removal or deactivation of the Yet Another bol.com Plugin version 1.4 or earlier until a patched version is available. 2. If plugin functionality is critical, implement a Web Application Firewall (WAF) with custom rules to detect and block suspicious input patterns targeting the PHP_SELF parameter, such as script tags or encoded payloads. 3. Sanitize and encode all user-controllable inputs reflected in web pages, especially $_SERVER variables, to prevent script injection. 4. Educate site administrators and users to avoid clicking on suspicious or unsolicited links that could exploit this vulnerability. 5. Monitor web server logs for unusual requests containing script payloads in URLs referencing yabp.php. 6. Consider isolating or sandboxing the plugin's output to limit the impact of any injected scripts. 7. Regularly audit and update all WordPress plugins to their latest versions and subscribe to security advisories related to bol.com integrations. 8. Implement Content Security Policy (CSP) headers to restrict execution of unauthorized scripts on affected pages.