paypal-ipn before 3.0.0 uses the `test_ipn` parameter (which is set by the PayPal IPN simulator) to determine if it should use the production PayPal site or the sandbox. With a bit of time, an attacker could craft a request using the simulator that would fool any application which does not explicitly check for test_ipn in production.

WebHybridClient.java in PayPal 5.3 and earlier for Android ignores SSL errors, which allows man-in-the-middle attackers to spoof servers and obtain sensitive information.

The WebHybridClient class in PayPal 5.3 and earlier for Android allows remote attackers to execute arbitrary JavaScript on the system.

The cp-contact-form-with-paypal (aka CP Contact Form with PayPal) plugin before 1.1.6 for WordPress has SQL injection via the cp_contactformpp_id parameter to cp_contactformpp.php.

Cross-site scripting (XSS) vulnerability in GetAuthDetails.html.php in PayPal PHP Merchant SDK (aka merchant-sdk-php) 3.9.1 allows remote attackers to inject arbitrary web script or HTML via the token parameter.

PayPal WPS ToolKit does not verify that the server hostname matches a domain name in the subject's Common Name (CN) or subjectAltName field of the X.509 certificate, which allows man-in-the-middle attackers to spoof SSL servers via an arbitrary valid certificate.

The PayPal module in Ubercart does not verify that the server hostname matches a domain name in the subject's Common Name (CN) or subjectAltName field of the X.509 certificate, which allows man-in-the-middle attackers to spoof SSL servers via an arbitrary valid certificate.

PayPal Payments Standard PHP Library before 20120427 does not verify that the server hostname matches a domain name in the subject's Common Name (CN) or subjectAltName field of the X.509 certificate, which allows man-in-the-middle attackers to spoof SSL servers via an arbitrary valid certificate, related to intentional disabling of certificate-validation checks through a "FALSE" value.

The PayPal Payments Pro module in Zen Cart does not verify that the server hostname matches a domain name in the subject's Common Name (CN) or subjectAltName field of the X.509 certificate, which allows man-in-the-middle attackers to spoof SSL servers via an arbitrary valid certificate, related to use of the PHP fsockopen function, a different vulnerability than CVE-2012-5805.

PayPal Invoicing does not verify that the server hostname matches a domain name in the subject's Common Name (CN) or subjectAltName field of the X.509 certificate, which allows man-in-the-middle attackers to spoof SSL servers via an arbitrary valid certificate.