Improper Certificate Validation in Apache Commons HttpClient

Apache Commons HttpClient 3.x, as used in Amazon Flexible Payments Service (FPS) merchant Java SDK and other products, 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.

Note that the Commons HttpClient project is end of life. It has been replaced by the Apache HttpComponents project in its HttpClient and HttpCore modules. CVE-2012-5783 has been patched in v4.0 of the Apache HttpComponents HttpClient module.