Red Hat Enterprise: RHSA-2012-0744-01 Moderate: Python DoS And XSS

Python is an interpreted, interactive, object-oriented programming language.
A denial of service flaw was found in the implementation of associative arrays (dictionaries) in Python. An attacker able to supply a large number of inputs to a Python application (such as HTTP POST request parameterssent to a web application) that are used as keys when inserting data into an array could trigger multiple hash function collisions, making array operations take an excessive amount of CPU time. To mitigate this issue, randomization has been added to the hash function to reduce the chance of an attacker successfully causing intentional collisions. (CVE-2012-1150)
Note: The hash randomization is not enabled by default as it may break applications that incorrectly depend on dictionary ordering. To enable the protection, the new "PYTHONHASHSEED" environment variable or the Python interpreter's "-R" command line option can be used. Refer to the python(1) manual page for details.
The RHSA-2012:0731 expat erratum must be installed with this update, which adds hash randomization to the Expat library used by the Python pyexpat module.
A flaw was found in the way the Python SimpleXMLRPCServer module handled clients disconnecting prematurely. A remote attacker could use this flaw to cause excessive CPU consumption on a server using SimpleXMLRPCServer. (CVE-2012-0845)
A flaw was found in the way the Python SimpleHTTPServer module generated directory listings. An attacker able to upload a file with a specially-crafted name to a server could possibly perform a cross-site scripting (XSS) attack against victims visiting a listing page generated by SimpleHTTPServer, for a directory containing the crafted file (if the victims were using certain web browsers). (CVE-2011-4940)
A race condition was found in the way the Python distutils module set file permissions during the creation of the .pypirc file. If a local user had access to the home directory of another user who is running distutils, they could use this flaw to gain access to that user's .pypirc file, which can contain usernames and passwords for code repositories. (CVE-2011-4944)
Red Hat would like to thank oCERT for reporting CVE-2012-1150. oCERT acknowledges Julian Wälde and Alexander Klink as the original reporters of CVE-2012-1150.
All Python users should upgrade to these updated packages, which contain backported patches to correct these issues.