Apache HttpClient versions prior to version 4.5.13 and 5.0.3 can misinterpret malformed authority component in request URIs passed to the library as java.net.URI object and pick the wrong target host for request execution.

org.apache.http.conn.ssl.AbstractVerifier in Apache HttpComponents HttpClient before 4.3.5 and HttpAsyncClient before 4.0.2 does not properly 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 a "CN=" string in a field in the distinguished name (DN) of a certificate, as demonstrated by the "foo,CN=www.apache.org" string in the O field.

Apache HttpClient 4.x before 4.1.1 in Apache HttpComponents, when used with an authenticating proxy server, sends the Proxy-Authorization header to the origin server, which allows remote web servers to obtain sensitive information by logging this header.