The set_debugreg hypercall in include/asm-x86/debugreg.h in Xen 4.0, 4.1, and 4.2, and Citrix XenServer 6.0.2 and earlier, when running on x86-64 systems, allows local OS guest users to cause a denial of service (host crash) by writing to the reserved bits of the DR7 debug control register.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Xenserver | Citrix | * | 6.0.2 (including) |
| Xen | Xen | 4.0.0 (including) | 4.0.0 (including) |
| Xen | Xen | 4.1.0 (including) | 4.1.0 (including) |
| Xen | Xen | 4.2.0 (including) | 4.2.0 (including) |
| Xen | Ubuntu | oneiric | * |
| Xen | Ubuntu | precise | * |
| Xen | Ubuntu | upstream | * |
| Xen-3.1 | Ubuntu | hardy | * |
| Xen-3.2 | Ubuntu | hardy | * |
| Xen-3.3 | Ubuntu | lucid | * |
| Xen-3.3 | Ubuntu | natty | * |