CVE-2021-4358 in WP DSGVO Tools Plugin
Summary
by MITRE • 06/07/2023
The WP DSGVO Tools (GDPR) plugin for WordPress is vulnerable to Stored Cross-Site Scripting via an unknown parameter in versions up to, and including, 3.1.23 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.
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Analysis
by VulDB Data Team • 04/09/2026
The WP DSGVO Tools plugin for WordPress represents a critical security vulnerability classified as CVE-2021-4358, which affects versions up to and including 3.1.23. This vulnerability manifests as a stored cross-site scripting flaw that exploits insufficient input sanitization and output escaping mechanisms within the plugin's codebase. The vulnerability operates through an unknown parameter that allows attackers to inject malicious scripts into the WordPress environment, creating a persistent threat that can compromise user sessions and execute unauthorized commands. The stored nature of this XSS vulnerability means that once injected, the malicious code remains embedded in the website's database and will execute whenever any user accesses the compromised page, making it particularly dangerous for widespread impact.
The technical exploitation of this vulnerability occurs through improper validation of user-supplied input data that flows into the plugin's output rendering mechanisms. When the plugin processes requests containing malicious script payloads, it fails to adequately sanitize the input before displaying it to users, creating an environment where attacker-controlled code can be executed within the context of legitimate user sessions. This flaw directly violates fundamental security principles outlined in the CWE-79 category for Cross-Site Scripting vulnerabilities, specifically manifesting as a stored XSS variant where the malicious payload is permanently stored on the server. The vulnerability's impact extends beyond simple script execution to potentially enable session hijacking, credential theft, and other advanced persistent threats that can compromise the entire WordPress installation.
The operational impact of CVE-2021-4358 creates significant risks for WordPress administrators and end users who rely on the plugin for GDPR compliance and data protection features. Unauthenticated attackers can exploit this vulnerability to inject malicious JavaScript code that executes in the browsers of unsuspecting users, potentially leading to data exfiltration, account takeovers, and further compromise of the WordPress environment. The vulnerability's presence in a plugin designed for data protection creates a particularly concerning scenario where attackers can exploit the very tool meant to secure user data. This creates a dangerous paradox where the security measure becomes a vector for exploitation, potentially affecting thousands of WordPress sites that have not yet updated to patched versions. The attack surface is broad as the vulnerability affects all users accessing pages that contain the malicious payload, regardless of their authentication status.
Mitigation strategies for CVE-2021-4358 must prioritize immediate action through plugin updates to versions that address the input sanitization and output escaping deficiencies. System administrators should implement comprehensive monitoring of their WordPress installations to detect any suspicious activity or unauthorized modifications that might indicate exploitation attempts. The implementation of Content Security Policy headers can provide additional defense-in-depth measures to prevent execution of unauthorized scripts even if exploitation occurs. Security professionals should also consider implementing web application firewalls to filter malicious requests and maintain regular security audits of WordPress plugins to ensure compliance with security best practices. Organizations should follow ATT&CK framework guidance for mitigating web application vulnerabilities, particularly focusing on preventing code injection attacks and implementing proper input validation controls. The vulnerability serves as a reminder of the critical importance of maintaining up-to-date security practices and the necessity of thorough code review processes for all third-party WordPress plugins to prevent similar issues from compromising user security and data integrity.