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This bulletin was written by Vigil@nce : https://vigilance.fr/offer

SYNTHESIS OF THE VULNERABILITY

A privileged attacker in the guest system can generate a memory
corruption via the IRET hypercall of Xen, in order to get hight
privileges on the host system.

Impacted products: XenServer, Debian, Fedora, SUSE Linux
Enterprise Desktop, SLES, Xen.

Severity: 2/4.

Creation date: 02/05/2017.

Revision date: 09/05/2017.

DESCRIPTION OF THE VULNERABILITY

The Xen product offers a way to chain hypervisor calls.

The IRET hypercall make the processor returns from guest kernel to
guest user program. The next hypercalls in a chain will then use
the wrong page table.

A privileged attacker in the guest system can therefore generate a
memory corruption via the IRET hypercall of Xen, in order to get
hight privileges on the host system.

ACCESS TO THE COMPLETE VIGIL@NCE BULLETIN

https://vigilance.fr/vulnerability/Xen-page-table-corruption-via-the-IRET-hypercall-22622