Debian Security Advisory DSA 2662-1 (xen - several vulnerabilities)

Summary
Multiple vulnerabilities have been discovered in the Xen hypervisor. The Common Vulnerabilities and Exposures project identifies the following problems: CVE-2013-1917 The SYSENTER instruction can be used by PV guests to accelerate system call processing. This instruction, however, leaves the EFLAGS register mostly unmodified. This can be used by malicious or buggy user space to cause the entire host to crash. CVE-2013-1919 Various IRQ related access control operations may not have the intended effect, potentially permitting a stub domain to grant its client domain access to an IRQ it doesn't have access to itself. This can be used by malicious or buggy stub domains kernels to mount a denial of service attack possibly affecting the whole system.
Solution
For the stable distribution (squeeze), these problems have been fixed in version 4.0.1-5.9. For the testing distribution (wheezy) and the unstable distribution (sid), these problems will be fixed soon. We recommend that you upgrade your xen packages.
Insight
Xen is a hypervisor providing services that allow multiple computer operating systems to execute on the same computer hardware concurrently.
Affected
xen on Debian Linux
Detection
This check tests the installed software version using the apt package manager.
References