Python 2.7 through 2.7.17, 3.5 through 3.5.9, 3.6 through 3.6.10, 3.7 through 3.7.6, and 3.8 through 3.8.1 allows an HTTP server to conduct Regular Expression Denial of Service (ReDoS) attacks against a client because of urllib.request.AbstractBasicAuthHandler catastrophic backtracking.
In Python (CPython) 3.6 through 3.6.10, 3.7 through 3.7.6, and 3.8 through 3.8.1, an insecure dependency load upon launch on Windows 7 may result in an attacker's copy of api-ms-win-core-path-l1-1-0.dll being loaded and used instead of the system's copy. Windows 8 and later are unaffected.
An exploitable denial-of-service vulnerability exists in the X509 certificate parser of Python.org Python 2.7.11 / 3.6.6. A specially crafted X509 certificate can cause a NULL pointer dereference, resulting in a denial of service. An attacker can initiate or accept TLS connections using crafted certificates to trigger this vulnerability.
The documentation XML-RPC server in Python through 2.7.16, 3.x through 3.6.9, and 3.7.x through 3.7.4 has XSS via the server_title field. This occurs in Lib/DocXMLRPCServer.py in Python 2.x, and in Lib/xmlrpc/server.py in Python 3.x. If set_server_title is called with untrusted input, arbitrary JavaScript can be delivered to clients that visit the http URL for this server.
An issue was discovered in Python through 2.7.16, 3.x through 3.5.7, 3.6.x through 3.6.9, and 3.7.x through 3.7.4. The email module wrongly parses email addresses that contain multiple @ characters. An application that uses the email module and implements some kind of checks on the From/To headers of a message could be tricked into accepting an email address that should be denied. An attack may be the same as in CVE-2019-11340; however, this CVE applies to Python more generally.