An issue was discovered in Xen through 4.14.x. The PCI passthrough code improperly uses register data. Code paths in Xen's MSI handling have been identified that act on unsanitized values read back from device hardware registers. While devices strictly compliant with PCI specifications shouldn't be able to affect these registers, experience shows that it's very common for devices to have out-of-spec "backdoor" operations that can affect the result of these reads. A not fully trusted guest may be able to crash Xen, leading to a Denial of Service (DoS) for the entire system. Privilege escalation and information leaks cannot be excluded. All versions of Xen supporting PCI passthrough are affected. Only x86 systems are vulnerable. Arm systems are not vulnerable. Only guests with passed through PCI devices may be able to leverage the vulnerability. Only systems passing through devices with out-of-spec ("backdoor") functionality can cause issues. Experience shows that such out-of-spec funct…

Improper authentication in Citrix XenMobile Server 10.12 before RP2, Citrix XenMobile Server 10.11 before RP4, Citrix XenMobile Server 10.10 before RP6 and Citrix XenMobile Server before 10.9 RP5 leads to the ability to access sensitive files.

Improper access control in Citrix XenMobile Server 10.12 before RP3, Citrix XenMobile Server 10.11 before RP6, Citrix XenMobile Server 10.10 RP6 and Citrix XenMobile Server before 10.9 RP5 allows access to privileged functionality.

Improper input validation in Citrix XenMobile Server 10.12 before RP3, Citrix XenMobile Server 10.11 before RP6, Citrix XenMobile Server 10.10 RP6 and Citrix XenMobile Server before 10.9 RP5 allows SQL Injection.

Insufficient protection of secrets in Citrix XenMobile Server 10.12 before RP3, Citrix XenMobile Server 10.11 before RP6, Citrix XenMobile Server 10.10 RP6 and Citrix XenMobile Server before 10.9 RP5 discloses credentials of a service account.

Improper access control in Citrix XenMobile Server 10.12 before RP2, Citrix XenMobile Server 10.11 before RP4, Citrix XenMobile Server 10.10 before RP6 and Citrix XenMobile Server before 10.9 RP5 and leads to the ability to read arbitrary files.

Improper input validation in Citrix XenMobile Server 10.12 before RP1, Citrix XenMobile Server 10.11 before RP4, Citrix XenMobile Server 10.11 before RP6 and Citrix XenMobile Server before 10.9 RP5 allows Cross-Site Scripting (XSS).

An issue was discovered in the Linux kernel 5.5 through 5.7.9, as used in Xen through 4.13.x for x86 PV guests. An attacker may be granted the I/O port permissions of an unrelated task. This occurs because tss_invalidate_io_bitmap mishandling causes a loss of synchronization between the I/O bitmaps of TSS and Xen, aka CID-cadfad870154.

An issue was discovered in Xen through 4.13.x, allowing x86 Intel HVM guest OS users to cause a host OS denial of service or possibly gain privileges because of insufficient cache write-back under VT-d. When page tables are shared between IOMMU and CPU, changes to them require flushing of both TLBs. Furthermore, IOMMUs may be non-coherent, and hence prior to flushing IOMMU TLBs, a CPU cache also needs writing back to memory after changes were made. Such writing back of cached data was missing in particular when splitting large page mappings into smaller granularity ones. A malicious guest may be able to retain read/write DMA access to frames returned to Xen's free pool, and later reused for another purpose. Host crashes (leading to a Denial of Service) and privilege escalation cannot be ruled out. Xen versions from at least 3.2 onwards are affected. Only x86 Intel systems are affected. x86 AMD as well as Arm systems are not affected. Only x86 HVM guests using hardware assisted paging …

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.