Joris van Rantwijk discovered that the Xen host did not correctly validate the contents of a Xen guests's grug.conf file. Xen guest root users could exploit this to run arbitrary commands on the host when the guest system was rebooted.

=========================================================== 
Ubuntu Security Notice USN-527-1           October 05, 2007
xen-3.0 vulnerability
CVE-2007-4993
==========================================================
A security issue affects the following Ubuntu releases:

Ubuntu 7.04

This advisory also applies to the corresponding versions of
Kubuntu, Edubuntu, and Xubuntu.

The problem can be corrected by upgrading your system to the
following package versions:

Ubuntu 7.04:
  xen-utils-3.0                   3.0.3-0ubuntu10.1

In general, a standard system upgrade is sufficient to affect the
necessary changes.

Details follow:

Joris van Rantwijk discovered that the Xen host did not correctly validate
the contents of a Xen guests's grug.conf file.  Xen guest root users could
exploit this to run arbitrary commands on the host when the guest system
was rebooted.


Updated packages for Ubuntu 7.04:

  Source archives:

          Size/MD5:    43307 2f531fea82cc88494f81bbdd050ef824
          Size/MD5:     1023 3336b4ce7f13d381400bb6d0a80cd0b7
          Size/MD5:  5465571 98ac5465ff111a3ff76a985bf755c6a5

  Architecture independent packages:

          Size/MD5:   533754 b65c9495bcfa717ed1a5b8c46f999402

  amd64 architecture (Athlon64, Opteron, EM64T Xeon):

          Size/MD5:    70804 ffc9f9d0ab7f8df7df2e0ffd8f08285c
          Size/MD5:    73492 dd35493b60f4792e345abda43d20aa8b
          Size/MD5:   420742 a1638f0e7cbbf5685b041abc158dfa8a
          Size/MD5:   271940 66492dd5d6a4c52fc97114d2bb983ffa
          Size/MD5:   317284 88a2027bff8d08983d0d8771859e68fd
          Size/MD5:   283572 8e9197196e594faf891ce535014b6c71

  i386 architecture (x86 compatible Intel/AMD):

          Size/MD5:    70800 0295889477fb1b8c83edb7cfe2b6872a
          Size/MD5:    69486 b24236890f2ba901e4852188a72ebb22
          Size/MD5:   416932 81e667521fe88fe02db3355b42bf5e5b
          Size/MD5:   269408 1c2d69bafb3ca2d540dc13105ac40e10
          Size/MD5:   251070 facaee8d4581cdbfe7682b30e87e8065
          Size/MD5:   298840 6a863568a47389b1d2990c97bdcb2620
          Size/MD5:   272848 90980654788696fad35a613fcc562a88