A denial of service flaw was found in the way python-backports-ssl_match_hostname, an implementation that brings the ssl.match_hostname() function from Python 3.2 to users of earlier versions of Python, performed matching of the certificate's name in the case it contained many '*' wildcard characters. A remote attacker, able to obtain valid certificate with its name containing a lot of '*' wildcard characters, could use this flaw to cause denial of service (excessive CPU time consumption) by issuing request to validate that certificate for / in an application using the python-backports-ssl_match_hostname functionality.
Upstream bug report:
This issue was discovered by Florian Weimer of Red Hat Product Security Team.
This issue affects the versions of the python-backports-ssl_match_hostname package as shipped with Fedora release of 17, 18, and Fedora EPEL-6. Please schedule an update (once there is final upstream patch available).
Created python-backports-ssl_match_hostname tracking bugs for this issue
Affects: fedora-all [bug 963187]
Affects: epel-6 [bug 963188]
and Python 3.2 case follow-up:
(will file independent Python 3.2 bug shortly - after the lunch)
*** This bug has been marked as a duplicate of bug 963260 ***