CVE-2023-4213 in Simplr Registration Form Plus+ Plugin
Summary
by MITRE • 09/13/2023
The Simplr Registration Form Plus+ plugin for WordPress is vulnerable to Insecure Direct Object References in versions up to, and including, 2.4.5. This is due to the plugin providing user-controlled access to objects, letting a user bypass authorization and access system resources. This makes it possible for authenticated attackers with subscriber-level permissions or above to change user passwords and potentially take over administrator accounts.
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Analysis
by VulDB Data Team • 04/10/2026
The Simplr Registration Form Plus+ plugin for WordPress presents a critical security vulnerability classified as Insecure Direct Object Reference under CVE-2023-4213. This vulnerability affects all versions up to and including 2.4.5, creating a significant risk for WordPress installations that rely on this plugin for user registration and management functionalities. The flaw resides in how the plugin handles object references, specifically allowing unauthorized access to system resources through direct manipulation of object identifiers.
The technical implementation of this vulnerability stems from the plugin's failure to properly validate and authorize user requests when accessing user-related objects. When users submit registration or profile update requests, the plugin accepts user-controlled input directly without sufficient authorization checks, enabling attackers to manipulate object references and gain access to resources they should not be permitted to access. This design flaw directly aligns with CWE-639, which defines Insecure Direct Object Reference as a condition where the application provides direct access to objects based on user-supplied input without proper authorization checks.
Authenticated attackers with subscriber-level permissions or higher can exploit this vulnerability to modify user passwords and potentially escalate their privileges to administrator accounts. The impact extends beyond simple password changes, as successful exploitation could lead to complete account takeover and unauthorized access to sensitive system resources. Attackers can leverage this vulnerability to access other users' accounts, modify user roles and permissions, and potentially compromise the entire WordPress installation. This represents a serious threat to system integrity and user data protection, as it allows for privilege escalation attacks that can undermine the security model of the entire platform.
The operational impact of this vulnerability is particularly concerning for WordPress administrators who may be unaware of the compromised plugin's presence within their system. Attackers can systematically target users with lower privileges and gradually escalate their access, making detection more challenging. The vulnerability's exploitation requires minimal technical expertise, making it attractive to threat actors seeking to compromise WordPress installations. Organizations should consider this vulnerability in their threat modeling and incident response planning, as it could serve as an initial access vector for more extensive attacks against their web infrastructure.
Mitigation strategies should prioritize immediate plugin updates to versions that address the Insecure Direct Object Reference vulnerability. Administrators should implement comprehensive monitoring of user activities and access patterns to detect potential exploitation attempts. Network segmentation and access controls can help limit the potential damage from successful attacks. Additionally, implementing proper input validation and authorization checks within the plugin's codebase would address the root cause of the vulnerability. Organizations should also conduct thorough security assessments of all installed plugins and themes to identify similar vulnerabilities that may exist within their WordPress environments. The remediation process should include verifying that the updated plugin properly implements access controls and authorization checks, ensuring that user requests are properly validated before granting access to system resources. This vulnerability highlights the importance of maintaining up-to-date security practices and the critical need for proper authorization mechanisms in web applications, particularly those handling user registration and authentication processes.