Citrix XenServer 4.1, 6.0, 5.6 SP2, 5.6 Feature Pack 1, 5.6 Common Criteria, 5.6, 5.5, 5.0, and 5.0 Update 3 contains a Local Privilege Escalation Vulnerability which could allow local users with access to a guest operating system to gain elevated privileges.

The Windows Guest Tools in Citrix XenServer 6.2 SP1 and earlier allows remote attackers to cause a denial of service (guest OS crash) via a crafted Ethernet frame.

Xen 4.6.x, 4.5.x, 4.4.x, 4.3.x, and earlier do not initialize x86 FPU stack and XMM registers when XSAVE/XRSTOR are not used to manage guest extended register state, which allows local guest domains to obtain sensitive information from other domains via unspecified vectors.

QEMU does not properly restrict write access to the PCI config space for certain PCI pass-through devices, which might allow local x86 HVM guests to gain privileges, cause a denial of service (host crash), obtain sensitive information, or possibly have other unspecified impact via unknown vectors.

The PV pagetable code in arch/x86/mm.c in Xen 4.7.x and earlier allows local 32-bit PV guest OS administrators to gain host OS privileges by leveraging fast-paths for updating pagetable entries.

Xen 4.5.x through 4.7.x do not implement Supervisor Mode Access Prevention (SMAP) whitelisting in 32-bit exception and event delivery, which allows local 32-bit PV guest OS kernels to cause a denial of service (hypervisor and VM crash) by triggering a safety check.