CVE-2025-4334: Critical Privilege Escalation Vulnerability in Simple User Registration Plugin for WordPress

Overview

The Simple User Registration plugin for WordPress, a popular tool used for streamlining user registration processes on numerous websites, is facing a serious security issue. The vulnerability, designated as CVE-2025-4334, allows for privilege escalation and can potentially lead to system compromise or data leakage. The vulnerability exists in all versions of the plugin up to and including 6.3. This issue is particularly critical due to the widespread use of WordPress, which means a large number of websites could potentially be affected.

Vulnerability Summary

CVE ID: CVE-2025-4334
Severity: Critical (9.8 CVSS score)
Attack Vector: Remote
Privileges Required: None
User Interaction: None
Impact: System Compromise, Data Leakage

Affected Products

Product | Affected Versions

Simple User Registration Plugin for WordPress | Up to and including 6.3

How the Exploit Works

The vulnerability originates from the inadequate restrictions on user meta values that can be supplied during the registration process. An attacker can manipulate these values to register as an administrator without the need for authentication. Once the attacker has admin privileges, they can compromise the system or leak sensitive data.

Conceptual Example Code

To exemplify, an attacker could potentially send a manipulated HTTP POST request to the registration endpoint, using a JSON object with malicious content to exploit the vulnerability. This could look something like:

POST /wp-json/user-registration/v1/users HTTP/1.1
Host: target.example.com
Content-Type: application/json
{
"username": "attacker",
"email": "attacker@example.com",
"password": "Password123",
"role": "administrator"
}

In the above example, the `”role”: “administrator”` line is the crucial point. This is where the attacker assigns themselves an admin role during the registration process. Under normal circumstances, the system should not allow this, but due to the vulnerability in the plugin, the system fails to adequately check and restrict these meta values.

Mitigation and Remediation

The most straightforward way to mitigate this vulnerability is to apply the patch provided by the vendor. If the patch cannot be applied immediately, using a Web Application Firewall (WAF) or Intrusion Detection System (IDS) to monitor and control incoming traffic can serve as a temporary mitigation strategy. These tools could potentially identify and block attempts to exploit the vulnerability.
Finally, it is crucial to regularly update all software, including plugins, as outdated software is often a prime target for cyber attackers exploiting known vulnerabilities.