Race condition in the virNetServerClientStartKeepAlive function in libvirt before 1.2.1 allows remote attackers to cause a denial of service (libvirtd crash) by closing a connection before a keepalive response is sent.

The lxcDomainGetMemoryParameters method in lxc/lxcdriver.c in libvirt 1.0.5 through 1.2.0 does not properly check the status of LXC guests when reading memory tunables, which allows local users to cause a denial of service (NULL pointer dereference and libvirtd crash) via a guest in the shutdown status, as demonstrated by the "virsh memtune" command.

Description of the problem:

Domblkstat is possible even with read-only connection, so whenever migration with spice is done and domblkstat gets called at the same time as qemuMonitorGetSpiceMigrationStatus(), there is certain possibility that the daemon crashes.

An unprivileged user able to issue commands to running libvirtd could use this flaw to crash libvirtd and prevent more privileged clients from working correctly.

Upstream fix: http://libvirt.org/git/?p=libvirt.git;a=commit;h=484cc321

Acknowledgements:

This issue was discovered by Marian Krcmarik of Red Hat.

It has been found that sending crafted RPC command with nparams set to 0 can lead to libvirtd accessing random memory, possibly leading to crash. A remote attacker could use this flaw to crash libvirtd (DoS).

Upstream proposed fix: https://www.redhat.com/archives/libvir-list/2012-July/msg01650.html

libvirt, possibly before 0.9.12, does not properly assign USB devices to virtual machines when multiple devices have the same vendor and product ID, which might cause the wrong device to be associated with a guest and might allow local users to access unintended USB devices.