Race condition in the FTPHandler class in ftpserver.py in pyftpdlib...

Vulnerability Description

Race condition in the FTPHandler class in ftpserver.py in pyftpdlib before 0.5.1 allows remote attackers to cause a denial of service (daemon outage) by establishing and then immediately closing a TCP connection, leading to the accept function having an unexpected return value of None, a different vulnerability than CVE-2010-3494.

References

• http://www.openwall.com/lists/oss-security/2010/09/11/2
• http://code.google.com/p/pyftpdlib/issues/detail?id=91
• http://code.google.com/p/pyftpdlib/source/browse/trunk/HISTORY
• https://bugs.launchpad.net/zodb/+bug/135108
• http://code.google.com/p/pyftpdlib/source/detail?r=439
• http://www.openwall.com/lists/oss-security/2010/09/24/3
• http://www.openwall.com/lists/oss-security/2010/09/22/3
• http://bugs.python.org/issue6706
• http://www.openwall.com/lists/oss-security/2010/09/09/6
• http://code.google.com/p/pyftpdlib/source/diff?spec=svn439&r=439&format=side&path=/trunk/pyftpdlib/ftpserver.py