libvirtd in libvirt before 0.9.0 does not use thread-safe error reporting, which allows remote attackers to cause a denial of service (crash) by causing multiple threads to report errors at the same time.
https://www.redhat.com/archives/libvir-list/2011-March/msg01087.html
https://bugzilla.redhat.com/show_bug.cgi?id=693391
http://www.ubuntu.com/usn/USN-1152-1
http://www.securityfocus.com/bid/47148
http://www.redhat.com/support/errata/RHSA-2011-0479.html
http://www.redhat.com/support/errata/RHSA-2011-0478.html
http://www.debian.org/security/2011/dsa-2280
http://support.avaya.com/css/P8/documents/100134583
http://securitytracker.com/id?1025477
http://secunia.com/advisories/44459
http://libvirt.org/git/?p=libvirt.git%3Ba=commit%3Bh=f44bfb7fb978c9313ce050a1c4149bf04aa0a670