CVE-2025-23693 in Secure CAPTCHA Plugin
Summary
by MITRE • 01/16/2025
Cross-Site Request Forgery (CSRF) vulnerability in Stanisław Skonieczny Secure CAPTCHA allows Stored XSS.This issue affects Secure CAPTCHA: from n/a through 1.2.
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Analysis
by VulDB Data Team • 02/10/2025
The vulnerability identified as CVE-2025-23693 represents a critical security flaw in the Secure CAPTCHA plugin developed by Stanisław Skonieczny. This issue manifests as a cross-site request forgery vulnerability that enables stored cross-site scripting attacks, creating a dangerous chain of exploitation possibilities for malicious actors. The vulnerability exists within the plugin's handling of user input and session management mechanisms, specifically affecting versions ranging from the initial release through version 1.2. The affected plugin is commonly used in wordpress environments to prevent automated spam submissions, making this vulnerability particularly concerning for website administrators and security professionals.
The technical implementation of this vulnerability stems from inadequate validation and sanitization of user-provided data within the CAPTCHA processing pipeline. When users submit forms that utilize the Secure CAPTCHA functionality, the system fails to properly verify the authenticity of requests through proper CSRF token implementation. This weakness allows attackers to craft malicious requests that appear legitimate to the server, enabling them to inject malicious scripts into the plugin's storage mechanisms. The stored XSS component emerges when these malicious payloads are subsequently served to other users who interact with the compromised CAPTCHA functionality, creating a persistent threat vector.
The operational impact of this vulnerability extends far beyond simple data theft or service disruption. Attackers can leverage this flaw to execute arbitrary code within users' browsers, potentially leading to complete session hijacking, credential theft, and unauthorized administrative access to affected websites. The stored nature of the XSS payload means that the attack can persist long after the initial compromise, affecting all users who encounter the malicious content. This vulnerability directly maps to CWE-352, which specifically addresses Cross-Site Request Forgery, and CWE-79, which covers Cross-Site Scripting. The attack surface is particularly dangerous when considering that CAPTCHA systems are often deployed to protect sensitive user interactions, making the compromise of such systems especially damaging to overall security postures.
Mitigation strategies for this vulnerability require immediate attention from system administrators and security teams. The primary recommendation involves upgrading to the latest version of the Secure CAPTCHA plugin where the CSRF protection mechanisms have been properly implemented. Organizations should also implement additional defensive measures such as Content Security Policy headers to limit the execution of unauthorized scripts, and comprehensive input validation routines to prevent malicious data from being stored within the system. Network monitoring should be enhanced to detect anomalous request patterns that may indicate CSRF attack attempts. The vulnerability demonstrates the critical importance of proper session management and CSRF token implementation, aligning with ATT&CK technique T1566 for credential access through social engineering and T1059 for execution through malicious scripts. Organizations should also consider implementing web application firewalls to detect and block known attack patterns targeting CAPTCHA systems and other authentication mechanisms.