The resolve_redirects function in sessions.py in requests 2.1.0 through 2.5.3 allows remote attackers to conduct session fixation attacks via a cookie without a host value in a redirect.
Requests (aka python-requests) before 2.3.0 allows remote servers to obtain sensitive information by reading the Proxy-Authorization header in a redirected request.
Requests (aka python-requests) before 2.3.0 allows remote servers to obtain a netrc password by reading the Authorization header in a redirected request.