scottpaterson Contact Form 7 Plugin up to 2.4.9 on WordPress cf7pp_paypal_ipn_handler data authenticity

Summaryinfo

A vulnerability identified as critical has been detected in scottpaterson Contact Form 7 Plugin up to 2.4.9 on WordPress. Affected by this issue is the function cf7pp_paypal_ipn_handler. This manipulation causes data authenticity. The identification of this vulnerability is CVE-2026-9189. It is possible to initiate the attack remotely. There is no exploit available. You should upgrade the affected component.

Detailsinfo

A vulnerability has been found in scottpaterson Contact Form 7 Plugin up to 2.4.9 on WordPress and classified as critical. Affected by this vulnerability is the function cf7pp_paypal_ipn_handler. The manipulation with an unknown input leads to a data authenticity vulnerability. The CWE definition for the vulnerability is CWE-345. The product does not sufficiently verify the origin or authenticity of data, in a way that causes it to accept invalid data. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

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.

The weakness was shared by Muni Nitish Kumar Yaddala. It is possible to read the advisory at wordfence.com. This vulnerability is known as CVE-2026-9189 since 05/21/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details of the vulnerability are known, but there is no available exploit.

Upgrading to version 2.4.6 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-33265). Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

Type

• WordPress Plugin

Vendor

• scottpaterson

Name

• Contact Form 7 Plugin

Version

• 2.4.0
• 2.4.1
• 2.4.2
• 2.4.3
• 2.4.4
• 2.4.5
• 2.4.6
• 2.4.7
• 2.4.8
• 2.4.9

CPE 2.3info

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CPE 2.2info

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Entryinfo

Be aware that VulDB is the high quality source for vulnerability data.

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