CVE-2021-24166 in Ninja Forms Contact Form
Summary
by MITRE • 04/06/2021
The wp_ajax_nf_oauth_disconnect from the Ninja Forms Contact Form – The Drag and Drop Form Builder for WordPress WordPress plugin before 3.4.34 had no nonce protection making it possible for attackers to craft a request to disconnect a site's OAuth connection.
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Analysis
by VulDB Data Team • 04/10/2021
The vulnerability identified as CVE-2021-24166 affects the Ninja Forms Contact Form plugin for WordPress, specifically targeting the wp_ajax_nf_oauth_disconnect endpoint. This issue exists in versions prior to 3.4.34 and represents a critical security flaw that undermines the integrity of the plugin's authentication mechanisms. The vulnerability stems from the absence of nonce protection within the OAuth disconnection functionality, creating an exploitable condition that allows unauthorized actors to manipulate the plugin's authentication state.
The technical flaw manifests as a lack of proper authentication verification within the WordPress AJAX endpoint responsible for handling OAuth disconnection requests. Nonce values serve as one-time tokens that verify the authenticity of requests in WordPress environments, preventing cross-site request forgery attacks. Without this protection, attackers can construct malicious requests that appear legitimate to the WordPress system, enabling them to disconnect OAuth connections without proper authorization. This weakness directly violates the principle of least privilege and undermines the security model of the WordPress plugin architecture.
The operational impact of this vulnerability extends beyond simple unauthorized access, potentially allowing attackers to compromise the entire OAuth authentication chain for affected WordPress sites. When an attacker successfully exploits this vulnerability, they can terminate legitimate OAuth connections, potentially disrupting legitimate user access or creating opportunities for further attacks. The vulnerability particularly affects sites that rely on OAuth for authentication with external services, as the unauthorized disconnection could lead to service disruption or create opportunities for credential theft. This flaw aligns with CWE-352, which specifically addresses Cross-Site Request Forgery vulnerabilities in web applications.
The security implications of CVE-2021-24166 can be analyzed through the lens of the MITRE ATT&CK framework, particularly under the T1566 technique for credential access through social engineering or unauthorized access. Attackers could leverage this vulnerability to create a false sense of security by disconnecting legitimate OAuth connections, potentially leading to more sophisticated attacks. The vulnerability also exposes the plugin to potential privilege escalation scenarios where attackers might use the OAuth disconnection as a stepping stone to broader system compromise. Organizations using affected versions of the Ninja Forms plugin face significant risk, as this vulnerability could be exploited in automated scanning campaigns targeting WordPress installations.
Mitigation strategies for CVE-2021-24166 center on immediate plugin updates to version 3.4.34 or later, which incorporates proper nonce protection for the OAuth disconnection endpoint. System administrators should also implement additional security measures including monitoring for unauthorized OAuth disconnection attempts, implementing rate limiting on authentication-related endpoints, and conducting comprehensive security audits of WordPress plugins. The fix addresses the core issue by introducing proper nonce validation that ensures only authorized requests can trigger the OAuth disconnection functionality, thereby restoring the intended security controls. Organizations should also consider implementing web application firewalls and security monitoring solutions to detect and prevent exploitation attempts targeting similar vulnerabilities in their WordPress environments.