CVE-2024-4133 in ARMember Plugin
Summary
by MITRE • 05/03/2024
The ARMember – Membership Plugin, Content Restriction, Member Levels, User Profile & User signup plugin for WordPress is vulnerable to Open Redirect in all versions up to, and including, 4.0.30. This is due to insufficient validation on the redirect url supplied via the redirect_to parameter. This makes it possible for unauthenticated attackers to redirect users to potentially malicious sites if they can successfully trick them into performing an action.
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Analysis
by VulDB Data Team • 06/13/2026
The ARMember WordPress plugin presents a critical open redirect vulnerability that affects all versions up to and including 4.0.30, creating a significant security risk for WordPress websites utilizing this membership management solution. This vulnerability stems from inadequate input validation mechanisms within the plugin's handling of the redirect_to parameter, which is commonly used for user redirection after authentication or membership actions. The flaw allows attackers to manipulate the redirection behavior by injecting malicious URLs into the redirect_to parameter, potentially compromising user security and website integrity.
The technical implementation of this vulnerability resides in the plugin's insufficient sanitization and validation of user-supplied redirect URLs. When users attempt to access restricted content or perform membership-related actions, the plugin accepts the redirect_to parameter without proper validation of the URL scheme or destination. This creates an environment where attackers can craft malicious URLs containing protocols such as javascript: or data: that could execute harmful code in the victim's browser context. The vulnerability specifically aligns with CWE-601 Open Redirect vulnerability classification, which occurs when an application redirects users to external sites without proper validation of the target URL. The issue represents a direct violation of secure coding practices that mandate input validation and output encoding for all user-controllable data elements.
The operational impact of this vulnerability extends beyond simple redirection attacks, as it can be leveraged for sophisticated phishing campaigns and social engineering attacks. Unauthenticated attackers can exploit this weakness to redirect users to malicious domains that appear legitimate, potentially stealing login credentials, personal information, or financial data. The vulnerability is particularly dangerous in the context of WordPress membership sites where users are already engaged in authentication processes, making them more susceptible to manipulation. Attackers can craft convincing URLs that appear to originate from the legitimate website, exploiting the trust relationship between users and the WordPress platform to gain unauthorized access to user accounts or sensitive data.
Security professionals should consider this vulnerability in relation to the ATT&CK framework's T1566 Initial Access technique, specifically the use of malicious links for credential theft and phishing attacks. The vulnerability's exploitation requires minimal technical skill and can be automated, making it attractive to threat actors seeking to maximize impact with minimal effort. Organizations using ARMember plugin versions up to 4.0.30 should implement immediate mitigations including plugin updates to versions that address the redirect validation issue, implementation of web application firewalls with URL validation rules, and user education regarding suspicious redirection attempts. Additionally, administrators should consider implementing network-level controls to monitor and block suspicious redirect patterns, as well as conducting regular security audits to identify other potential vulnerabilities in the WordPress ecosystem. The vulnerability demonstrates the critical importance of proper input validation in web applications and serves as a reminder that even seemingly benign features like redirect functionality can become security risks when not properly secured.