CVE-2018-21012 in cf7-invisible-recaptcha Plugin
Summary
by MITRE
The cf7-invisible-recaptcha plugin before 1.3.2 for WordPress has XSS.
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Analysis
by VulDB Data Team • 12/18/2023
The vulnerability CVE-2018-21012 affects the cf7-invisible-recaptcha plugin for WordPress, specifically versions prior to 1.3.2, and represents a cross-site scripting vulnerability that poses significant security risks to WordPress installations. This issue arises from inadequate input validation and output escaping mechanisms within the plugin's codebase, allowing malicious actors to inject malicious scripts into web pages viewed by other users. The vulnerability specifically impacts the plugin's handling of user-supplied data in the invisible reCAPTCHA implementation, creating an attack surface where unauthorized code execution can occur through web browser manipulation.
The technical flaw manifests when the plugin fails to properly sanitize and escape user input before rendering it within HTML output contexts. This weakness enables attackers to craft malicious payloads that exploit the plugin's processing of form submissions and reCAPTCHA verification responses. The vulnerability can be exploited through various vectors including contact form submissions, plugin configuration settings, or any user-controllable input fields that the plugin processes. The lack of proper context-aware escaping means that attacker-controlled data can be interpreted as executable JavaScript code rather than benign text, leading to unauthorized actions performed on behalf of authenticated users.
The operational impact of this vulnerability extends beyond simple script injection, as it can enable attackers to perform a wide range of malicious activities including session hijacking, credential theft, data exfiltration, and privilege escalation. When exploited successfully, the XSS vulnerability allows attackers to execute arbitrary JavaScript code within the browser context of authenticated users, potentially compromising entire WordPress installations. The attack can be particularly dangerous in environments where administrators or trusted users interact with the vulnerable plugin, as these users may have elevated privileges that could be leveraged to gain deeper system access. The vulnerability affects not only the plugin's immediate functionality but also the broader security posture of WordPress sites that rely on this third-party component.
Mitigation strategies for CVE-2018-21012 require immediate action to upgrade the affected plugin to version 1.3.2 or later, which includes proper input validation and output escaping mechanisms. Security professionals should implement comprehensive input sanitization routines that follow established security standards such as those outlined in the CWE-79 category for cross-site scripting vulnerabilities. Additionally, administrators should conduct thorough security audits of their WordPress installations to identify any other potentially vulnerable plugins or themes that may exhibit similar weaknesses. The ATT&CK framework categorizes this vulnerability under the T1059.007 technique for JavaScript-based command execution, making it a critical target for defensive measures including web application firewalls, content security policies, and regular security monitoring. Organizations should also implement proper security configuration management practices that include regular plugin updates, vulnerability scanning, and security hardening procedures to prevent similar issues from occurring in the future.