CVE-2025-58673

Executive Summary

CVE-2025-58673 is a Code Injection vulnerability (CWE-94) affecting the WP User Frontend WordPress plugin by weDevs, up to and including version 4.1.12. This flaw allows an authenticated attacker with low privileges to inject arbitrary code, potentially leading to full site compromise. The vulnerability resides in improper control of code generation within the plugin, enabling malicious input to be executed as PHP code. As a WordPress ecosystem issue, this affects sites using the plugin for frontend user management, registration, and profile editing. No public exploit or patch is currently available, making proactive detection and mitigation critical.

Supply Chain & Package Security

This vulnerability is specific to the WordPress plugin ecosystem. The WP User Frontend plugin is distributed via the official WordPress Plugin Directory and can be installed directly from the WordPress admin dashboard. Organizations should inventory all WordPress installations and verify the version of WP User Frontend in use. Since no patch exists, consider removing or disabling the plugin until an update is released. Monitor the plugin’s changelog and security advisories for patch announcements.

CVSS Breakdown & Threat Level

• CVSS Score: 5.4 (Medium)
• Attack Vector: Network (AV:N)
• Attack Complexity: Low (AC:L)
• Privileges Required: Low (PR:L) – requires authenticated user
• User Interaction: None (UI:N)
• Scope: Unchanged (S:U)
• Confidentiality Impact: Low (C:L)
• Integrity Impact: Low (I:L)
• Availability Impact: Low (A:L)

Threat Level: Medium. While the CVSS score is moderate, the potential for code injection in a widely-used WordPress plugin elevates the risk. An attacker could escalate privileges, inject backdoors, or exfiltrate data.

Deep Dive & Mechanics

The vulnerability stems from improper sanitization of user-supplied input that is later used in code generation. In WP User Frontend, the plugin allows users to submit forms, edit profiles, and manage content from the frontend. The code injection likely occurs when the plugin processes shortcodes, custom fields, or template tags without adequate validation. An attacker with subscriber-level access could inject PHP code via a form field or profile update, which is then executed when the plugin renders the content.

Attack Vector:

1. Attacker logs in as a subscriber or higher.
2. Attacker submits a form or updates a profile field containing malicious PHP code (e.g., <?php system($_GET['cmd']); ?>).
3. The plugin stores the input without proper sanitization.
4. When the plugin generates output (e.g., displaying the user profile), the injected code is executed on the server.

Root Cause: Lack of input validation and output escaping in code generation routines, likely in functions that handle shortcode parsing or template rendering.

Vulnerable vs. Patched Code

Since no patch is available, a hypothetical fix would involve:

Vulnerable Code (Conceptual):

// Vulnerable: Directly evaluates user input
$user_input = $_POST['custom_field'];
eval("echo '$user_input';");

Patched Code (Conceptual):

// Patched: Sanitize and escape output
$user_input = sanitize_text_field($_POST['custom_field']);
echo esc_html($user_input);

The patched version would use WordPress built-in functions like sanitize_text_field() and esc_html() to prevent code execution.

Exploitation & Lab Setup

Red Team

Prerequisites:

• WordPress installation with WP User Frontend <= 4.1.12
• Valid user account (subscriber or higher)

Exploitation Steps:

1. Log in to WordPress as a subscriber.
2. Navigate to a frontend form (e.g., profile edit).
3. Inject PHP code into a text field (e.g., <?php file_put_contents('/tmp/evil.php', '<?php system($_GET["c"]); ?>'); ?>).
4. Submit the form.
5. Trigger the code execution by viewing the profile or a page that renders the field.
6. Access the injected shell: http://target.com/wp-content/uploads/evil.php?c=id

Note: No public exploit code is available. The above is a conceptual demonstration.

Blue Team

Detection & Response:

• Monitor for unusual PHP file creation in upload directories.
• Alert on eval() or system() calls in web server logs.
• Use WAF rules to block PHP code in form fields.
• Implement file integrity monitoring for WordPress core and plugin files.

Hunting Queries:

• Search for <?php in custom fields or user meta.
• Look for recent file modifications in /wp-content/uploads/.
• Review logs for POST requests to form endpoints with suspicious payloads.

Indicators of Compromise (IOCs)

• File IOCs:
  • Unexpected PHP files in /wp-content/uploads/ or /wp-content/plugins/wp-user-frontend/
  • Modified plugin files (check file hashes)
• Network IOCs:
  • Outbound connections to unknown IPs from the web server
  • HTTP requests containing <?php in POST data
• Log IOCs:
  • Web server logs showing eval() or system() calls
  • Error logs with PHP parse errors from injected code
• User IOCs:
  • New admin accounts created by non-admin users
  • Suspicious user meta containing PHP code

Detection Engineering

YARA Rule

rule CVE_2025_58673_WP_User_Frontend_Code_Injection {
    meta:
        description = "Detects PHP code injection attempts in WP User Frontend plugin"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-58673"
    strings:
        $php_tag = "<?php"
        $short_tag = "<?="
        $eval_func = "eval("
        $system_func = "system("
        $exec_func = "exec("
    condition:
        any of ($php_tag, $short_tag) and any of ($eval_func, $system_func, $exec_func)
}

Sigma Rule

title: CVE-2025-58673 - WP User Frontend Code Injection
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects PHP code injection attempts via WP User Frontend plugin
author: Valters IT
date: 2025-04-10
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2025-58673
logsource:
    category: webserver
    product: apache
    service: access_combined
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: 'wp-user-frontend'
        cs-uri-query|contains|all:
            - 'action=update_profile'
            - 'wp_nonce'
    keywords:
        - '<?php'
        - 'eval('
        - 'system('
    condition: selection and keywords
falsepositives:
    - Legitimate PHP code in user profiles (rare)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2025-58673 WP User Frontend Code Injection Attempt"; flow:to_server,established; content:"POST"; http_method; content:"wp-user-frontend"; http_uri; content:"<?php"; http_client_body; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin until a patch is released.
2. Remove or restrict user roles that can submit forms.
3. Implement Web Application Firewall (WAF) rules to block PHP code in POST data.
4. Monitor logs for exploitation attempts.

Long-term Fix:

• Apply the official patch once released by weDevs.
• Update to the latest version of WP User Frontend.
• Conduct a security audit of all WordPress plugins.

Workarounds:

• Use a security plugin (e.g., Wordfence) to block malicious input.
• Add custom code to sanitize form fields:

add_filter('wpuf_update_profile', 'sanitize_profile_fields');
function sanitize_profile_fields($data) {
    foreach ($data as $key => $value) {
        $data[$key] = sanitize_text_field($value);
    }
    return $data;
}

Valters IT
Securing Digital Frontiers