CVE-2025-13384 is a Missing Authorization vulnerability (CWE-862) found in the CP Contact Form with PayPal plugin for WordPress, affecting all versions up to and including 1.3.56. The vulnerability stems from the plugin exposing an unauthenticated endpoint triggered via the 'cp_contactformpp_ipncheck' query parameter. This endpoint mimics PayPal's Instant Payment Notification (IPN) mechanism but lacks critical security controls such as authentication, nonce verification, and validation of PayPal IPN signatures. Consequently, attackers can send arbitrary POST requests containing forged payment data fields like payment_status, txn_id, and payer_email to this endpoint. The plugin then processes these forged notifications as legitimate payment confirmations, marking form submissions as paid without any actual financial transaction. The vulnerability is remotely exploitable without any authentication or user interaction, increasing its risk profile. The CVSS v3.1 base score is 7.5 (High), reflecting the ease of exploitation and the significant impact on data integrity, as attackers can manipulate payment status records. While no public exploits have been reported yet, the flaw presents a clear risk to organizations relying on this plugin for payment processing, potentially leading to financial fraud and loss of trust. The lack of patch links suggests that a fix may not yet be available, emphasizing the need for immediate mitigation steps.

For European organizations, this vulnerability poses a substantial risk to financial integrity and operational trustworthiness. Organizations using the CP Contact Form with PayPal plugin to handle payments or donations may face fraudulent payment confirmations, leading to unauthorized access to goods, services, or benefits without actual payment. This can result in direct financial losses, accounting discrepancies, and reputational damage. Additionally, the manipulation of payment records can undermine customer trust and complicate compliance with financial regulations such as GDPR, which mandates accurate transaction records. The vulnerability's remote and unauthenticated exploitability means attackers can operate from anywhere, increasing the threat landscape. E-commerce businesses, non-profits accepting donations, and service providers relying on this plugin are particularly vulnerable. The absence of nonce or signature validation also means automated exploitation or mass fraud attempts could be feasible, amplifying potential damage.

1. Immediately restrict access to the 'cp_contactformpp_ipncheck' endpoint by implementing web server rules (e.g., .htaccess, nginx config) to allow only trusted IP addresses or block all external access until a patch is available. 2. Monitor web server logs for unusual POST requests to this endpoint, especially those with suspicious payment_status or txn_id values, to detect potential exploitation attempts. 3. If possible, disable the CP Contact Form with PayPal plugin temporarily or replace it with a more secure payment processing solution until an official patch is released. 4. Implement additional validation layers at the application level, such as verifying payment confirmations directly with PayPal's official IPN or webhook services, ensuring that payment notifications are genuine. 5. Educate site administrators on the risks and encourage timely updates once a security patch is published. 6. Conduct regular audits of payment records to identify discrepancies that may indicate fraudulent confirmations. 7. Consider deploying Web Application Firewalls (WAFs) with custom rules to detect and block forged IPN-like requests targeting this vulnerability.