Alex Gaynor reports:

""" When Python's standard library HTTP clients (httplib, urllib, urllib2, xmlrpclib) are used to access resources with HTTPS, by default the certificate is not checked against any trust store, nor is the hostname in the certificate checked against the requested host. It was possible to configure a trust root to be checked against, however there were no faculties for hostname checking.

This made MITM attacks against the HTTP clients trivial, and violated RFC 2818 (http://tools.ietf.org/html/rfc2818#section-3).

Python 2.7.9 has been issued to resolve this issue. It is also resolved in 3.4.3, which has not yet been released. """

CVE request: http://seclists.org/oss-sec/2014/q4/1022

Julian Wälde and Alexander Klink reported a flaw in the hash function used in the implementation of the Python dictionaries (associative arrays).

A specially-crafted set of keys could trigger hash function collisions, which degrade dictionary performance by changing hash table operations complexity from an expected/average O(1) to the worst case O(n). Reporters were able to find colliding strings efficiently using meet in the middle attack.

As various web application frameworks for Python automatically pre-fill certain dictionaries with data from the HTTP request (such as GET or POST parameters) for Python web application, a remote attacker could use this flaw to make Python interpreter use excessive amount of CPU time by sending a POST request with large amount of parameters which hash to the same value.

This problem is similar to the issue that was previously reported for and fixed in e.g. perl: http://www.cs.rice.edu/~scrosby/hash/CrosbyWallachUsenixSec2003.pdf

Stack-based buffer overflow in Python 2.4.2 and earlier, running on Linux 2.6.12.5 under gcc 4.0.3 with libc 2.3.5, allows local users to cause a "stack overflow," and possibly gain privileges, by running a script from a current working directory that has a long name, related to the realpath function. NOTE: this might not be a vulnerability. However, the fact that it appears in a programming language interpreter could mean that some applications are affected, although attack scenarios might be limited because the attacker might already need to cross privilege boundaries to cause an exploitable program to be placed in a directory with a long name; or, depending on the method that Python uses to determine the current working directory, setuid applications might be affected.