httplib2 prior to version 0.10.1, after an initial connection is made, 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.
A malicious server which responds with long series of \xa0 characters in the www-authenticate header may cause Denial of Service (CPU burn while parsing header) of the httplib2 client accessing said server.
Attacker controlling unescaped part of uri for httplib2.Http.request() could change request headers and body, send additional hidden requests to same server. Impacts software that uses httplib2 with uri constructed by string concatenation, as opposed to proper urllib building with escaping.