EUVD-2026-33265
GHSA-vr4h-g9wj-2p4g
Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Primary rating from NVD · only source for this CVE.
CVSS VectorNVD
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Lifecycle Timeline
2DescriptionCVE.org
The Contact Form 7 - PayPal & Stripe Add-on plugin for WordPress is vulnerable to Payment Bypass via Insufficient Verification of Data Authenticity in all versions up to, and including, 2.4.9. Although cf7pp_paypal_ipn_handler() correctly validates IPN authenticity by posting back to PayPal with cmd=_notify-validate, it fails to compare the IPN payload's mc_gross (payment amount), mc_currency, or receiver_email fields against the corresponding stored order values before passing the attacker-controlled invoice field directly to cf7pp_complete_payment(), which marks the order completed after only an integer cast with no amount verification. This makes it possible for unauthenticated attackers to mark arbitrary high-value pending orders as fully paid by making a minimal real PayPal payment and crafting an IPN whose invoice parameter references the targeted order, effectively completing purchases without tendering the required payment amount.
AnalysisAI
Payment bypass in the Contact Form 7 - PayPal & Stripe Add-on for WordPress (all versions up to and including 2.4.9) permits unauthenticated attackers to complete arbitrary pending orders without tendering the required payment amount. The IPN handler correctly authenticates PayPal callbacks via the cmd=_notify-validate round-trip, but then blindly trusts the attacker-controlled invoice field and passes it to cf7pp_complete_payment() without verifying that mc_gross, mc_currency, or receiver_email in the IPN match the stored order values - resulting in full order completion triggered by a minimal real payment. No public exploit code has been identified at time of analysis and this CVE is not listed in the CISA KEV catalog, but the direct financial incentive and low attack complexity elevate real-world priority beyond what the medium CVSS score alone implies.
Technical ContextAI
The vulnerability resides in the PayPal IPN (Instant Payment Notification) handler of the Contact Form 7 - PayPal & Stripe Add-on plugin (CPE: cpe:2.3:a:scottpaterson:contact_form_7_-_paypal_&_stripe_add-on:*:*:*:*:*:*:*:*). PayPal IPN is a server-to-server callback where PayPal POSTs transaction data to a merchant endpoint; the merchant must echo the payload back to PayPal with cmd=_notify-validate to confirm the notification is genuine. The plugin's cf7pp_paypal_ipn_handler() correctly performs this handshake (paypal_handler.php:L75 and L106 across tags 2.4.6 and 2.4.8), satisfying envelope authenticity under CWE-345 (Insufficient Verification of Data Authenticity). However, IPN authenticity only confirms that PayPal sent the notification - it does not bind the notification to a specific order amount. By skipping comparison of mc_gross, mc_currency, and receiver_email against the stored order record, the handler allows the attacker-supplied invoice field to determine which order gets completed. That field is passed to cf7pp_complete_payment() (functions.php:L31) after only an integer cast, with no amount verification - breaking the transactional integrity of the payment flow and allowing one real payment of any amount to satisfy any pending order.
RemediationAI
Administrators should update the Contact Form 7 - PayPal & Stripe Add-on plugin to a version beyond 2.4.9 via the WordPress dashboard immediately; a code fix has been committed in WordPress plugin Trac changeset 3551197 (https://plugins.trac.wordpress.org/changeset/3551197/contact-form-7-paypal-add-on), though the specific released version number containing this fix is not independently confirmed in available data - verify the installed version exceeds 2.4.9 after updating. As a compensating control prior to patching, administrators can temporarily disable or restrict access to the PayPal IPN endpoint at the server or WAF layer; note this will halt automated order completion and require manual payment reconciliation until the patch is applied. Administrators should also audit recent completed orders against PayPal transaction records to identify orders completed with payment amounts that do not match the order total, which would indicate prior exploitation. Monitor the Wordfence advisory at https://www.wordfence.com/threat-intel/vulnerabilities/id/5e274781-1c20-4224-bc10-26dadb9b1e07 for confirmed patched release version details.
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External POC / Exploit Code
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