Red Hat Enterprise Linux 5 RHSA-2008:0194-01 Critical: Xen DoS Risk

The xen packages contain tools for managing the virtual machine monitor in Red Hat Virtualization.
These updated packages fix the following security issues:
Daniel P. Berrange discovered that the hypervisor's para-virtualized framebuffer (PVFB) backend failed to validate the format of messages serving to update the contents of the framebuffer. This could allow a malicious user to cause a denial of service, or compromise the privileged domain (Dom0). (CVE-2008-1944)
Markus Armbruster discovered that the hypervisor's para-virtualized framebuffer (PVFB) backend failed to validate the frontend's framebuffer description. This could allow a malicious user to cause a denial of service, or to use a specially crafted frontend to compromise the privileged domain (Dom0). (CVE-2008-1943)
Chris Wright discovered a security vulnerability in the QEMU block format auto-detection, when running fully-virtualized guests. Such fully-virtualized guests, with a raw formatted disk image, were able to write a header to that disk image describing another format. This could allow such guests to read arbitrary files in their hypervisor's host. (CVE-2008-2004)
Ian Jackson discovered a security vulnerability in the QEMU block device drivers backend. A guest operating system could issue a block device request and read or write arbitrary memory locations, which could lead to privilege escalation. (CVE-2008-0928)
Tavis Ormandy found that QEMU did not perform adequate sanity-checking of data received via the "net socket listen" option. A malicious local administrator of a guest domain could trigger this flaw to potentially execute arbitrary code outside of the domain. (CVE-2007-5730)
Steve Kemp discovered that the xenbaked daemon and the XenMon utility communicated via an insecure temporary file. A malicious local administrator of a guest domain could perform a symbolic link attack, causing arbitrary files to be truncated. (CVE-2007-3919)
As well, in the previous xen packages, it was possible for Dom0 to fail to flush data from a fully-virtualized guest to disk, even if the guest explicitly requested the flush. This could cause data integrity problems on the guest. In these updated packages, Dom0 always respects the request to flush to disk.
Users of xen are advised to upgrade to these updated packages, which resolve these issues.