CVE-2025-46442: Loan Calculator CSRF Vulnerability

CVE-2025-46442 Overview

CVE-2025-46442 is a Cross-Site Request Forgery (CSRF) vulnerability in the WordPress Loan Calculator plugin (repayment-calculator) developed by Casey Johnson. This vulnerability enables attackers to execute Stored Cross-Site Scripting (XSS) attacks by leveraging the lack of proper CSRF protection in the plugin's administrative functions.

The vulnerability allows an attacker to trick an authenticated administrator into performing unintended actions, which can result in persistent malicious scripts being stored within the WordPress installation. Once stored, these scripts execute in the browsers of any users who view the affected pages.

Critical Impact

This CSRF-to-Stored-XSS chain vulnerability allows attackers to inject persistent malicious scripts into WordPress sites, potentially compromising administrative sessions and site visitors.

Affected Products

• WordPress Loan Calculator plugin (repayment-calculator) versions through 1.3
• WordPress installations using affected plugin versions

Discovery Timeline

• 2025-04-24 - CVE-2025-46442 published to NVD
• 2026-04-15 - Last updated in NVD database

Technical Details for CVE-2025-46442

Vulnerability Analysis

This vulnerability represents a chained attack scenario combining two distinct web application security weaknesses: Cross-Site Request Forgery (CWE-352) and Stored Cross-Site Scripting. The Loan Calculator plugin fails to implement proper anti-CSRF tokens in its administrative form submissions, allowing attackers to craft malicious requests that execute in the context of an authenticated administrator's session.

When a logged-in administrator visits an attacker-controlled page or clicks a malicious link, the forged request submits arbitrary data to the plugin's settings or content storage mechanisms. Because the plugin also lacks proper output encoding and input sanitization, the attacker-supplied payload is stored and subsequently rendered as executable JavaScript to other users.

Root Cause

The root cause of this vulnerability is the absence of nonce verification in the plugin's form handling functions. WordPress provides built-in CSRF protection through its nonce system (wp_nonce_field() and wp_verify_nonce()), but the Loan Calculator plugin fails to implement these security controls. Additionally, the plugin does not properly sanitize user input before storing it in the database or escape output before rendering it to the browser.

Attack Vector

The attack vector involves social engineering combined with web-based exploitation. An attacker must first craft a malicious HTML page or email containing a form that auto-submits to the vulnerable WordPress endpoint. The attack proceeds as follows:

1. The attacker identifies a WordPress site using the vulnerable Loan Calculator plugin
2. A crafted page containing a hidden form with XSS payload is created
3. The attacker entices an authenticated WordPress administrator to visit the malicious page
4. The form automatically submits to the target WordPress site, storing the XSS payload
5. Subsequent visitors to the affected pages have the malicious script execute in their browsers

The vulnerability is exploitable through the network without requiring any privileges on the target system. The attacker needs only to convince an administrator to click a link while authenticated to the WordPress dashboard.

Detection Methods for CVE-2025-46442

Indicators of Compromise

• Unexpected or malicious JavaScript code appearing in loan calculator widget output or settings
• Unusual administrative changes to plugin configuration without administrator action
• Browser console errors or unexpected script execution on pages containing the loan calculator
• Web server logs showing POST requests to plugin endpoints from external referrers

Detection Strategies

• Review WordPress plugin settings for any unauthorized modifications to Loan Calculator configurations
• Implement Content Security Policy (CSP) headers to detect and block unauthorized inline script execution
• Monitor web application firewall logs for requests containing script tags or JavaScript event handlers targeting the plugin
• Audit database tables associated with the Loan Calculator plugin for suspicious content

Monitoring Recommendations

• Enable WordPress activity logging to track all administrative changes and plugin modifications
• Configure alerting for changes to plugin settings made during unusual hours or from unexpected IP addresses
• Implement real-time monitoring for DOM modifications indicative of XSS attacks on pages using the loan calculator
• Review HTTP referer headers for administrative POST requests to identify potential CSRF attacks

How to Mitigate CVE-2025-46442

Immediate Actions Required

• Deactivate and remove the Loan Calculator plugin (repayment-calculator) version 1.3 or earlier from all WordPress installations
• Audit affected WordPress sites for any stored malicious content in plugin-related database tables
• Review administrator accounts for any unauthorized changes or suspicious activity
• Consider implementing a Web Application Firewall (WAF) with CSRF and XSS protection rules

Patch Information

As of the published vulnerability data, no official patch has been confirmed for this vulnerability. Site administrators should monitor the Patchstack Vulnerability Report for updates on available fixes.

If the plugin author releases an update, verify it addresses CSRF protection through WordPress nonce implementation and properly sanitizes all user input before storage and output.

Workarounds

• Remove the vulnerable Loan Calculator plugin and use an alternative loan calculator solution with proper security controls
• Implement server-side Content Security Policy headers to mitigate the impact of any stored XSS payloads
• Restrict administrative access to WordPress by IP address or VPN to reduce CSRF attack surface
• Use browser extensions or security plugins that provide additional CSRF protection for authenticated sessions

# Add Content Security Policy headers in .htaccess to mitigate XSS impact
<IfModule mod_headers.c>
    Header set Content-Security-Policy "default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline';"
    Header set X-XSS-Protection "1; mode=block"
    Header set X-Content-Type-Options "nosniff"
</IfModule>