CVE-2024-2020 in Calculated Fields Form Professional Plugin
Summary
by MITRE • 03/13/2024
The Calculated Fields Form plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the form page href parameter in all versions up to, and including, 5.1.56 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. Exploitation requires the professional version or higher.
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Analysis
by VulDB Data Team • 05/24/2025
The Calculated Fields Form plugin for WordPress represents a widely used tool for creating dynamic forms with calculation capabilities, making it a critical component in many web applications. This vulnerability exists within the plugin's handling of the form page href parameter, which is processed without adequate input sanitization measures. The flaw affects all versions up to and including 5.1.56, creating a persistent security risk that can be exploited by attackers without authentication requirements. The vulnerability specifically targets the professional version of the plugin or higher, indicating that organizations using the standard version may be unaffected, though the broader implications remain concerning.
The technical nature of this vulnerability constitutes a stored cross-site scripting flaw that allows attackers to inject malicious scripts into form pages through the href parameter. This occurs because the plugin fails to properly sanitize user input before processing and storing it within the application's data structures. The lack of output escaping means that when legitimate users access pages containing the injected scripts, the malicious code executes within their browser context. The vulnerability manifests as a classic stored XSS attack vector where the malicious payload is permanently stored on the server and executed whenever the affected page is accessed.
The operational impact of this vulnerability extends beyond simple script execution, as it can enable attackers to perform various malicious activities including session hijacking, credential theft, and data exfiltration. Unauthenticated attackers can leverage this vulnerability to compromise user sessions and potentially escalate privileges within the WordPress environment. The attack requires no user interaction beyond accessing the malicious page, making it particularly dangerous as it can silently compromise users who visit compromised pages. The professional version requirement suggests that the vulnerability may be more prevalent in enterprise environments where advanced features are utilized, though the potential for widespread impact remains significant.
Mitigation strategies should focus on immediate plugin updates to versions that address the sanitization and escaping issues, with particular attention to ensuring that all input parameters are properly validated and escaped before processing. Organizations should implement input validation mechanisms that follow established security standards including those referenced in CWE-79, which specifically addresses cross-site scripting vulnerabilities. Network-level protections such as web application firewalls can provide additional defense-in-depth measures, though these should not replace proper code-level fixes. Security monitoring should be enhanced to detect unusual patterns in form processing and parameter handling, with particular focus on identifying potential exploitation attempts through the href parameter. Regular security audits of WordPress plugins and themes should be conducted to identify similar vulnerabilities that may exist in other components of the web application stack.