Bug 963186

Summary: python-backports-ssl_match_hostname: Denial of service when matching certificate with many '*' wildcard characters
Product: [Other] Security Response Reporter: Jan Lieskovsky <jlieskov>
Component: vulnerabilityAssignee: Red Hat Product Security <security-response-team>
Status: CLOSED DUPLICATE QA Contact:
Severity: low Docs Contact:
Priority: low    
Version: unspecifiedCC: fweimer, ian
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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Fixed In Version: Doc Type: Bug Fix
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Last Closed: 2013-05-15 14:50:18 UTC Type: ---
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description Jan Lieskovsky 2013-05-15 11:02:05 UTC 
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:
[1] http://bugs.python.org/issue17980

Acknowledgements:

This issue was discovered by Florian Weimer of Red Hat Product Security Team.
Comment 1 Jan Lieskovsky 2013-05-15 11:04:40 UTC 
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).
Comment 2 Jan Lieskovsky 2013-05-15 11:07:04 UTC 
Created python-backports-ssl_match_hostname tracking bugs for this issue

Affects: fedora-all [bug 963187]
Affects: epel-6 [bug 963188]
Comment 3 Jan Lieskovsky 2013-05-15 11:37:20 UTC 
CVE request:
  http://www.openwall.com/lists/oss-security/2013/05/15/6

and Python 3.2 case follow-up:
  http://www.openwall.com/lists/oss-security/2013/05/15/7
(will file independent Python 3.2 bug shortly - after the lunch)
Comment 4 Jan Lieskovsky 2013-05-15 14:50:18 UTC 

*** This bug has been marked as a duplicate of bug 963260 ***