CVE-2019-10160: Critical severity Python Python vulnerability

A security regression for CVE-2019-9636 was discovered in python's functions urllib.parse.urlsplit and urllib.parse.urlparse, introduced with commit d537ab0ff9767ef024f26246899728f0116b1ec3. No upstream python version is affected by this regression but the vulnerable commit may already have been included downstream as part of the original fix for CVE-2019-9636.

Affected python versions ignore the user/password part before @ in the netloc component of a URL, thus it still allows an attacker to exploit the vulnerability as in CVE-2019-9636. Those functions do not properly handle URLs encoded with Punycode/Internationalizing Domain Names in Applications (IDNA), which may result in a wrong domain name (specifically the netloc component of URL - user@domain:port) being returned by those functions. When an application parses user-supplied URLs to store cookies, authentication credentials, or other kind of information, it is possible for an attacker to provide specially crafted URLs to make the application locate host-related information (e.g. cookies, authentication data) and send them to a different host than where it should, unlike if the URLs had been correctly parsed. The result of an attack may vary based on the application.

External Reference https://python-security.readthedocs.io/vuln/urlsplit-nfkc-normalization2.html

Vulnerable commit https://github.com/python/cpython/commit/d537ab0ff9767ef024f26246899728f0116b1ec3

Upstream patch https://github.com/python/cpython/commit/8d0ef0b5edeae52960c7ed05ae8a12388324f87e