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An issue was discovered in Xen through 4.13.x, allowing Arm guest OS users to cause a hypervisor crash because of a missing alignment check in VCPUOP_register_vcpu_info. The hypercall VCPUOP_register_vcpu_info is used by a guest to register a shared region with the hypervisor. The region will be mapped into Xen address space so it can be directly accessed. On Arm, the region is accessed with instructions that require a specific alignment. Unfortunately, there is no check that the address provided by the guest will be correctly aligned. As a result, a malicious guest could cause a hypervisor crash by passing a misaligned address. A malicious guest administrator may cause a hypervisor crash, resulting in a Denial of Service (DoS). All Xen versions are vulnerable. Only Arm systems are vulnerable. x86 systems are not affected.
Base Score: 4.9
Impact Score: 6.9
Exploitability Score: 3.9
Base Score: 6.5
Impact Score: 4
Exploitability Score: 2
cpe:2.3:o:xen:xen:*:*:*:*:*:*:arm:* versions from 4.8.0 to 4.13.1 (inclusive)
|149066||Xen Missing Alignment Check DoS (XSA-327)||Nessus||Misc.|
|138925||GLSA-202007-02 : Xen: Multiple vulnerabilities||Nessus||Gentoo Local Security Checks|
|138864||Fedora 31 : xen (2020-76cf2b0f0a)||Nessus||Fedora Local Security Checks|
|138535||Fedora 32 : xen (2020-fbc13516af)||Nessus||Fedora Local Security Checks|
|138394||Debian DSA-4723-1 : xen - security update||Nessus||Debian Local Security Checks|