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SYNTHESIS OF THE VULNERABILITY

An attacker in a guest system can generate a memory corruption
with a Segment Override of Xen, in order to trigger a denial of
service, and possibly to execute code on the host system.

– Impacted products: XenServer, Debian, Fedora, Unix (platform)
– Severity: 2/4
– Creation date: 10/03/2015

DESCRIPTION OF THE VULNERABILITY

The Xen product emulates x86 processors. An x86 instruction can
use a Segment Override. For example:
mov ax, [es:1234]

However, if the Segment Override is encoded with some operands, a
memory corruption occurs.

An attacker in a guest system can therefore generate a memory
corruption with a Segment Override of Xen, in order to trigger a
denial of service, and possibly to execute code on the host system.

ACCESS TO THE COMPLETE VIGIL@NCE BULLETIN

http://vigilance.fr/vulnerability/Xen-memory-corruption-via-Segment-Override-16357