URL Redirection to Untrusted Site ('Open Redirect')
The CGIHandler class in Python before 2.7.12 does not protect against the HTTP_PROXY variable name clash in a CGI script, which could allow a remote attacker to redirect HTTP requests.
CWE-601 - Open Redirect
An open redirect attack employs a URL parameter, HTML refresh tags, or a DOM based location change to exploit the trust of a vulnerable domain to direct the users to a malicious website. The attack could lead to higher severity vulnerabilities such as unauthorized access control, account takeover, XSS, and more.