When making requests through a Requests Session, if the first request is made with verify=False to disable cert verification, all subsequent requests to the same origin will continue to ignore cert verification regardless of changes to the value of verify. This behavior will continue for the lifecycle of the connection in the connection pool.
Since Requests v2.3.0, Requests has been vulnerable to potentially leaking Proxy-Authorization headers to destination servers, specifically during redirects to an HTTPS origin. This is a product of how rebuild_proxies is used to recompute and reattach the Proxy-Authorization header to requests when redirected. Note this behavior has only been observed to affect proxied requests when credentials are supplied in the URL user information component (e.g. https://username:password@proxy:8080). Current vulnerable behavior(s): HTTP → …
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.
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.
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.
The Requests package through 2.19.1 before 2018-09-14 for Python sends an HTTP Authorization header to an http URI upon receiving a same-hostname https-to-http redirect, which makes it easier for remote attackers to discover credentials by sniffing the network.
Algorithmic complexity vulnerability in the ssl.match_hostname function and unspecified versions of python-backports-ssl_match_hostname as used for older Python versions, allows remote attackers to cause a denial of service (CPU consumption) via multiple wildcard characters in the common name in a certificate.
When using digest authentication with a wrong password, requests will retry the request for infinity. This makes the package vulnerable to Denial of Service (DoS).