Michael Tokarev uploaded new packages for qemu-kvm
which fixed the following security issues:

CVE-2011-0011

   Setting the VNC password to an empty string silently disabled
   all authentication.

CVE-2011-1750

   The virtio-blk driver performed insufficient validation of
   read/write I/O from the guest instance, which could lead to
   denial of service or privilege escalation.

CVE-2011-1751

   Incorrect memory handling during the removal of ISA devices in KVM
   could lead to denial of service of the execution of arbitrary code.

CVE-2011-2512

   incorrect sanitising of virtio queue commands in KVM could
   lead to denial of service of the execution of arbitrary code.

CVE-2010-2784

  The subpage MMIO initialization functionality in the subpage_register
  function in exec.c in KVM does not properly select the index for
  access to the callback array, which allows guest OS users to cause
  a denial of service (guest OS crash) or possibly gain privileges via
  unspecified vectors.

For the lenny-backports distribution the problem has been fixed
in version 0.12.5+dfsg-5+squeeze4~bpo50+1.

Upgrade instructions
--------------------

If you don't use pinning (see [1]) you have to update the package
manually via "apt-get -t lenny-backports install <packagelist>" with
the packagelist of your installed packages affected by this update.
[1] <https://backports.debian.org/Instructions>

We recommend to pin (in /etc/apt/preferences) the backports repository
to 200 so that new versions of installed  backports will be installed
automatically.

  Package: *
  Pin: release a=lenny-backports
  Pin-Priority: 200

We recommend that you upgrade your qemu-kvm packages.