CVE-2021-38335 is a Reflected Cross-Site Scripting (XSS) vulnerability identified in the Wise Agent Capture Forms WordPress plugin, specifically affecting version 1.0 and earlier. The vulnerability arises from improper handling of the $_SERVER["PHP_SELF"] variable within the ~/WiseAgentCaptureForm.php file. This variable reflects the current script's filename and path, and when not properly sanitized, it can be manipulated by an attacker to inject arbitrary JavaScript code. When a victim visits a crafted URL containing malicious script code embedded in the PHP_SELF value, the injected script executes in the context of the victim's browser. This can lead to theft of session cookies, redirection to malicious sites, or other client-side attacks. The vulnerability is classified under CWE-79, which pertains to improper neutralization of input leading to XSS. The CVSS v3.1 base score is 6.1 (medium severity), with the vector indicating network attack vector (AV:N), low attack complexity (AC:L), no privileges required (PR:N), user interaction required (UI:R), scope changed (S:C), and low impact on confidentiality and integrity (C:L/I:L) but no impact on availability (A:N). No known exploits in the wild have been reported, and no official patches are linked in the provided data. The vulnerability affects only the specified version 1.0 of the plugin, which is used within WordPress environments to capture leads or form submissions. Since the attack requires user interaction (victim clicking a malicious link), exploitation is somewhat limited but still poses a significant risk, especially in environments where users have elevated privileges or sensitive data is accessible via the plugin interface.

For European organizations using the Wise Agent Capture Forms plugin version 1.0, this vulnerability poses a risk primarily to the confidentiality and integrity of user sessions and data. Attackers can exploit the reflected XSS to execute malicious scripts in the context of authenticated users, potentially leading to session hijacking, credential theft, or unauthorized actions performed on behalf of the user. This can compromise customer data, internal user accounts, or administrative functions if the plugin is accessible to privileged users. While availability is not directly impacted, the reputational damage and potential regulatory consequences under GDPR for data breaches involving personal data could be significant. The scope of impact is limited to websites running the vulnerable plugin version, but given WordPress's widespread use in Europe, even a small market share of this plugin could expose multiple organizations. The requirement for user interaction reduces automated exploitation risk, but targeted phishing campaigns could effectively leverage this vulnerability. European organizations in sectors such as real estate, marketing, or customer relationship management—where lead capture forms are common—may be particularly affected.

1. Immediate upgrade or removal: Organizations should verify if they are using Wise Agent Capture Forms version 1.0 and upgrade to a patched version if available. If no patch exists, consider removing the plugin entirely or replacing it with a secure alternative. 2. Input sanitization: Developers maintaining the plugin should implement proper sanitization and encoding of the $_SERVER["PHP_SELF"] variable to neutralize malicious input before outputting it to the page. 3. Web Application Firewall (WAF): Deploy WAF rules that detect and block reflected XSS payloads targeting the vulnerable endpoint, especially those manipulating PHP_SELF parameters. 4. User awareness: Educate users about the risks of clicking suspicious links, particularly those that may contain unusual URL parameters. 5. Content Security Policy (CSP): Implement strict CSP headers to restrict the execution of inline scripts and reduce the impact of XSS attacks. 6. Monitoring and logging: Enable detailed logging of web requests to detect anomalous URL patterns indicative of attempted exploitation. 7. Regular vulnerability scanning: Incorporate scanning tools that can detect outdated or vulnerable WordPress plugins to proactively identify exposure.