CVE-2025-24636: MachForm Shortcode CSRF Vulnerability

CVE-2025-24636 Overview

CVE-2025-24636 is a Cross-Site Request Forgery (CSRF) vulnerability in the MachForm Shortcode WordPress plugin developed by Rick Laymance. This vulnerability enables attackers to leverage CSRF to inject malicious scripts that are persistently stored (Stored XSS), affecting all users who subsequently view the compromised content. The chained nature of this vulnerability—CSRF leading to Stored XSS—significantly increases its potential impact on WordPress sites utilizing this plugin.

Critical Impact

Attackers can exploit this CSRF vulnerability to inject persistent malicious scripts into WordPress sites, potentially compromising administrator sessions, stealing user credentials, or distributing malware to site visitors.

Affected Products

• MachForm Shortcode WordPress Plugin versions up to and including 1.4.1
• WordPress sites using the vulnerable machform-shortcode plugin

Discovery Timeline

• 2025-01-24 - CVE-2025-24636 published to NVD
• 2026-04-15 - Last updated in NVD database

Technical Details for CVE-2025-24636

Vulnerability Analysis

This vulnerability combines two distinct attack vectors: Cross-Site Request Forgery (CSRF) and Stored Cross-Site Scripting (XSS). The MachForm Shortcode plugin fails to implement proper CSRF token validation on critical form submission endpoints, allowing attackers to craft malicious requests that execute actions on behalf of authenticated administrators.

When a logged-in administrator visits a malicious page controlled by the attacker, their browser automatically submits a forged request to the vulnerable plugin endpoint. Because the plugin does not verify the legitimacy of the request origin, the malicious payload is accepted and stored in the WordPress database. This stored payload then executes whenever any user—including other administrators—views the affected content.

The CSRF-to-Stored-XSS attack chain is particularly dangerous because it requires minimal user interaction while achieving persistent compromise of the affected WordPress installation.

Root Cause

The root cause of this vulnerability is the absence of CSRF protection mechanisms in the MachForm Shortcode plugin. WordPress provides built-in nonce verification functions (wp_nonce_field() and wp_verify_nonce()) specifically designed to prevent CSRF attacks, but the vulnerable plugin versions do not implement these safeguards on sensitive form handling endpoints.

Additionally, the plugin fails to properly sanitize and escape user-supplied input before storing it in the database, enabling the secondary Stored XSS condition. This combination of missing CSRF tokens and inadequate input validation creates the exploitable attack chain.

Attack Vector

The attack follows a multi-stage process:

1. Reconnaissance: The attacker identifies a WordPress site running the vulnerable MachForm Shortcode plugin version 1.4.1 or earlier
2. Payload Crafting: The attacker creates a malicious HTML page containing a hidden form that auto-submits to the vulnerable plugin endpoint with an XSS payload
3. Social Engineering: The attacker tricks a WordPress administrator into visiting the malicious page while authenticated
4. Exploitation: The administrator's browser automatically submits the forged request, and the malicious script is stored in the WordPress database
5. Persistence: The stored XSS payload executes for all subsequent visitors to the affected page, potentially stealing session cookies, performing actions as victims, or redirecting users to malicious sites

The attack does not require the attacker to have any authentication to the target WordPress site—only that they can lure an authenticated administrator to an external malicious page.

Detection Methods for CVE-2025-24636

Indicators of Compromise

• Unexpected JavaScript or HTML content in MachForm shortcode configurations or stored settings
• Unusual outbound connections from client browsers to unknown external domains when viewing pages with MachForm shortcodes
• Suspicious administrator activity logs showing configuration changes without corresponding legitimate sessions
• Browser console errors or unexpected script execution warnings on pages containing MachForm elements

Detection Strategies

• Review WordPress audit logs for modifications to MachForm Shortcode plugin settings, especially those made without corresponding administrative actions
• Implement Content Security Policy (CSP) headers to detect and block unauthorized inline script execution
• Deploy web application firewalls (WAF) with rules to identify CSRF attack patterns and XSS payloads targeting WordPress plugins
• Conduct regular security scans of WordPress installations to identify outdated or vulnerable plugins

Monitoring Recommendations

• Enable and monitor WordPress activity logging plugins to track all administrative changes
• Configure browser-based monitoring to detect unexpected script execution on WordPress admin and public pages
• Set up alerts for modifications to plugin settings tables in the WordPress database
• Monitor HTTP referrer headers for administrative actions to identify potential CSRF attempts originating from external sites

How to Mitigate CVE-2025-24636

Immediate Actions Required

• Update the MachForm Shortcode plugin to a patched version that includes CSRF protection and proper input sanitization
• Audit all existing MachForm shortcode content and settings for potentially injected malicious scripts
• Temporarily deactivate the plugin if an update is not immediately available
• Review WordPress administrator accounts for any signs of compromise and rotate credentials if suspicious activity is detected

Patch Information

Users should check the official WordPress plugin repository or the Patchstack Vulnerability Report for updated version information and patch availability. The vulnerability affects all versions of MachForm Shortcode from initial release through 1.4.1.

Workarounds

• Deactivate and remove the MachForm Shortcode plugin if it is not essential to site functionality until a patch is available
• Implement strict Content Security Policy headers to mitigate the impact of any stored XSS payloads
• Restrict WordPress administrator sessions to known IP addresses to reduce the likelihood of successful CSRF exploitation
• Use a Web Application Firewall (WAF) with rules specifically designed to detect and block CSRF and XSS attacks targeting WordPress plugins
• Educate administrators about the risks of visiting untrusted links while authenticated to WordPress

# WordPress configuration hardening - add to wp-config.php or .htaccess
# Implement Content Security Policy header to mitigate XSS impact
# Add to .htaccess for Apache servers:
Header set Content-Security-Policy "script-src 'self'; object-src 'none';"

# For wp-config.php, consider defining trusted hosts:
# define('WP_HTTP_BLOCK_EXTERNAL', true);
# define('WP_ACCESSIBLE_HOSTS', 'api.wordpress.org,*.github.com');