The smtplib library in CPython (aka Python) before 2.7.12, 3.x before 3.4.5, and 3.5.x before 3.5.2 does not return an error when StartTLS fails, which might allow man-in-the-middle attackers to bypass the TLS protections by leveraging a network position between the client and the registry to block the StartTLS command, aka a "StartTLS stripping attack."

Affected: Ubuntu:14.04:LTS: python2.7, Ubuntu:14.04:LTS: python3.4, Ubuntu:16.04:LTS: python2.7, Ubuntu:16.04:LTS: python3.5

It was discovered that the smtplib library in Python did not return an error when StartTLS fails. A remote attacker could possibly use this to expose sensitive information. (CVE-2016-0772)

Rémi Rampin discovered that Python would not protect CGI applications from contents of the HTTP_PROXY environment variable when based on the contents of the Proxy header from HTTP requests. A remote attacker could possibly use this to cause a CGI application to redirect outgoing HTTP requests. (CVE-2016-1000110)

Insu Yun discovered an integer overflow in the zipimporter module in Python that could lead to a heap-based overflow. An attacker could use this to craft a special zip file that when read by Python could possibly execute arbitrary code. (CVE-2016-5636)

Guido Vranken discovered that the urllib modules in Python did not properly handle carriage return line feed (CRLF) in headers. A remote attacker could use this to craft URLs that inject arbitrary HTTP headers. This issue only affected Ubuntu 12.04 LTS and Ubuntu 14.04 LTS. (CVE-2016-5699)