CVE-2025-57977: Flexible PDF Invoices CSRF Vulnerability

CVE-2025-57977 Overview

A Cross-Site Request Forgery (CSRF) vulnerability has been identified in the Flexible PDF Invoices for WooCommerce & WordPress plugin developed by wpdesk. This vulnerability allows attackers to trick authenticated users into performing unintended actions on the affected WordPress site by crafting malicious requests that exploit the absence of proper CSRF token validation.

CSRF vulnerabilities enable attackers to forge requests on behalf of legitimate users who have already authenticated to the target application. When a user with administrative privileges visits a malicious page while authenticated to their WordPress dashboard, the attacker can leverage this vulnerability to perform unauthorized actions such as modifying plugin settings, generating fraudulent invoices, or altering financial records within the invoicing system.

Critical Impact

Attackers can exploit this CSRF vulnerability to perform unauthorized actions on behalf of authenticated WordPress administrators, potentially compromising invoice generation workflows and financial data integrity within WooCommerce stores.

Affected Products

• Flexible PDF Invoices for WooCommerce & WordPress plugin versions up to and including 6.0.13
• WordPress installations running the vulnerable wpdesk flexible-invoices plugin
• WooCommerce stores utilizing the affected invoicing functionality

Discovery Timeline

• 2025-09-22 - CVE-2025-57977 published to NVD
• 2026-04-15 - Last updated in NVD database

Technical Details for CVE-2025-57977

Vulnerability Analysis

This CSRF vulnerability exists due to insufficient validation of request origins within the Flexible PDF Invoices plugin. The plugin fails to properly implement nonce verification or referrer checking on sensitive administrative actions, allowing attackers to craft malicious forms or links that execute privileged operations when accessed by authenticated administrators.

The vulnerability is classified under CWE-352 (Cross-Site Request Forgery), which describes the scenario where a web application does not sufficiently verify whether a well-formed, valid, consistent request was intentionally provided by the user who submitted it. In the context of this WordPress plugin, state-changing operations related to invoice management can be triggered without proper origin validation.

Root Cause

The root cause of this vulnerability stems from missing or inadequate CSRF protection mechanisms within the plugin's request handling logic. WordPress provides built-in functions such as wp_nonce_field(), wp_verify_nonce(), and check_admin_referer() to protect against CSRF attacks, but the vulnerable versions of this plugin do not properly implement these security measures on critical administrative endpoints.

When processing form submissions or AJAX requests that modify plugin settings or invoice data, the application fails to validate that the request originated from a legitimate source within the WordPress admin interface, leaving it susceptible to cross-origin request exploitation.

Attack Vector

The attack vector for this vulnerability involves social engineering combined with crafted malicious web content. An attacker would need to:

1. Identify an administrative user of a WordPress site running the vulnerable plugin
2. Craft a malicious HTML page containing hidden forms or JavaScript that targets vulnerable plugin endpoints
3. Entice the authenticated administrator to visit the malicious page (via phishing email, compromised website, etc.)
4. Upon page load, the victim's browser automatically submits the forged request to the WordPress site with the user's existing session credentials

The attack does not require the attacker to have any prior authentication to the target WordPress installation. The malicious page can be hosted on any domain, and the victim's browser will include their WordPress session cookies when making the forged request.

Since no verified code examples are available for this vulnerability, administrators should refer to the Patchstack WordPress Vulnerability Report for detailed technical information about the vulnerable endpoints and exploitation mechanics.

Detection Methods for CVE-2025-57977

Indicators of Compromise

• Unexpected changes to invoice settings or configurations without corresponding administrator activity logs
• Suspicious referrer headers in web server logs showing external domains initiating requests to plugin administrative endpoints
• Unexplained invoice modifications, deletions, or generations that don't correlate with legitimate user actions
• Browser history or proxy logs showing administrator sessions accessing untrusted external websites shortly before plugin changes occurred

Detection Strategies

• Monitor WordPress audit logs for administrative actions on the Flexible PDF Invoices plugin that lack corresponding user interface interactions
• Implement web application firewall (WAF) rules to detect and block cross-origin requests to WordPress admin endpoints
• Review server access logs for POST requests to plugin-specific endpoints with external or missing referrer headers
• Deploy browser-based security extensions for administrators that warn against potential CSRF attacks

Monitoring Recommendations

• Enable comprehensive WordPress activity logging using security plugins to track all plugin configuration changes
• Configure server-side logging to capture full request headers including Origin and Referer for forensic analysis
• Implement real-time alerting for bulk or automated changes to invoice-related data within WooCommerce
• Regularly audit plugin settings and invoice records for unauthorized modifications

How to Mitigate CVE-2025-57977

Immediate Actions Required

• Update the Flexible PDF Invoices for WooCommerce & WordPress plugin to a version newer than 6.0.13 that includes CSRF protection fixes
• Review recent invoice and plugin configuration changes for any unauthorized modifications
• Instruct WordPress administrators to log out of active sessions when not actively managing the site
• Implement additional security headers such as SameSite cookie attributes to reduce CSRF attack surface

Patch Information

Users should update to the latest version of the Flexible PDF Invoices for WooCommerce & WordPress plugin that addresses this CSRF vulnerability. Check the official wpdesk plugin repository or the WordPress plugin directory for patched versions. The Patchstack vulnerability report provides additional details on the security fix.

Workarounds

• Restrict administrative access to the WordPress dashboard by IP address using .htaccess or server firewall rules
• Implement a Web Application Firewall (WAF) with CSRF protection rules to block malicious cross-origin requests
• Use browser extensions that block cross-site request forgery attempts for administrative users
• Limit the number of users with administrative privileges and ensure they follow security best practices when browsing

# Apache .htaccess example to restrict wp-admin access by IP
<Directory /var/www/html/wp-admin>
    Order Deny,Allow
    Deny from all
    Allow from 192.168.1.100
    Allow from 10.0.0.0/24
</Directory>