Xen through 4.7.x allows local ARM guest OS users to cause a denial of service (host crash) via vectors involving a (1) data or (2) prefetch abort with the ESR_EL2.EA bit set.

An issue was discovered in Xen through 4.12.x allowing Arm domU attackers to cause a denial of service (infinite loop) involving a compare-and-exchange operation.

An issue was discovered in Xen through 4.11.x allowing x86 PV guest OS users to cause a denial of service by leveraging a long-running operation that exists to support restartability of PTE updates.

An issue was discovered in Xen through 4.14.x. A guest may access xenstore paths via absolute paths containing a full pathname, or via a relative path, which implicitly includes /local/domain/$DOMID for their own domain id. Management tools must access paths in guests' namespaces, necessarily using absolute paths. oxenstored imposes a pathname limit that is applied solely to the relative or absolute path specified by the client. Therefore, a guest can create paths in its own namespace which are too long for management tools to access. Depending on the toolstack in use, a malicious guest administrator might cause some management tools and debugging operations to fail. For example, a guest administrator can cause "xenstore-ls -r" to fail. However, a guest administrator cannot prevent the host administrator from tearing down the domain. All systems using oxenstored are vulnerable. Building and using oxenstored is the default in the upstream Xen distribution, if the Ocaml compiler is available. Systems using C xenstored are not vulnerable.

Xen 3.3.x through 4.5.x enables logging for PCI MSI-X pass-through error messages, which allows local x86 HVM guests to cause a denial of service (host disk consumption) via certain invalid operations.

GNTTABOP_swap_grant_ref in Xen 4.2 through 4.5 does not check the grant table operation version, which allows local guest domains to cause a denial of service (NULL pointer dereference) via a hypercall without a GNTTABOP_setup_table or GNTTABOP_set_version.

QEMU, as used in Xen 3.3.x through 4.5.x, does not properly restrict access to PCI command registers, which might allow local HVM guest users to cause a denial of service (non-maskable interrupt and host crash) by disabling the (1) memory or (2) I/O decoding for a PCI Express device and then accessing the device, which triggers an Unsupported Request (UR) response.

Xen 3.3.x through 4.5.x and the Linux kernel through 3.19.1 do not properly restrict access to PCI command registers, which might allow local guest OS users to cause a denial of service (non-maskable interrupt and host crash) by disabling the (1) memory or (2) I/O decoding for a PCI Express device and then accessing the device, which triggers an Unsupported Request (UR) response.

An issue was discovered in Xen 4.6 through 4.14.x. When acting upon a guest XS_RESET_WATCHES request, not all tracking information is freed. A guest can cause unbounded memory usage in oxenstored. This can lead to a system-wide DoS. Only systems using the Ocaml Xenstored implementation are vulnerable. Systems using the C Xenstored implementation are not vulnerable.

An issue was discovered in Xen through 4.14.x. When they require assistance from the device model, x86 HVM guests must be temporarily de-scheduled. The device model will signal Xen when it has completed its operation, via an event channel, so that the relevant vCPU is rescheduled. If the device model were to signal Xen without having actually completed the operation, the de-schedule / re-schedule cycle would repeat. If, in addition, Xen is resignalled very quickly, the re-schedule may occur before the de-schedule was fully complete, triggering a shortcut. This potentially repeating process uses ordinary recursive function calls, and thus could result in a stack overflow. A malicious or buggy stubdomain serving a HVM guest can cause Xen to crash, resulting in a Denial of Service (DoS) to the entire host. Only x86 systems are affected. Arm systems are not affected. Only x86 stubdomains serving HVM guests can exploit the vulnerability.

An issue was discovered in Xen through 4.14.x. When a Xenstore watch fires, the xenstore client that registered the watch will receive a Xenstore message containing the path of the modified Xenstore entry that triggered the watch, and the tag that was specified when registering the watch. Any communication with xenstored is done via Xenstore messages, consisting of a message header and the payload. The payload length is limited to 4096 bytes. Any request to xenstored resulting in a response with a payload longer than 4096 bytes will result in an error. When registering a watch, the payload length limit applies to the combined length of the watched path and the specified tag. Because watches for a specific path are also triggered for all nodes below that path, the payload of a watch event message can be longer than the payload needed to register the watch. A malicious guest that registers a watch using a very large tag (i.e., with a registration operation payload length close to the 4096 byte limit) can cause the generation of watch events with a payload length larger than 4096 bytes, by writing to Xenstore entries below the watched path. This will result in an error condition in xenstored. This error can result in a NULL pointer dereference, leading to a crash of xenstored. A malicious guest administrator can cause xenstored to crash, leading to a denial of service. Following a xenstored crash, domains may continue to run, but management operations will be impossible. Only C xenstored is affected, oxenstored is not affected.

An issue was discovered in Xen 4.14.x. When moving IRQs between CPUs to distribute the load of IRQ handling, IRQ vectors are dynamically allocated and de-allocated on the relevant CPUs. De-allocation has to happen when certain constraints are met. If these conditions are not met when first checked, the checking CPU may send an interrupt to itself, in the expectation that this IRQ will be delivered only after the condition preventing the cleanup has cleared. For two specific IRQ vectors, this expectation was violated, resulting in a continuous stream of self-interrupts, which renders the CPU effectively unusable. A domain with a passed through PCI device can cause lockup of a physical CPU, resulting in a Denial of Service (DoS) to the entire host. Only x86 systems are vulnerable. Arm systems are not vulnerable. Only guests with physical PCI devices passed through to them can exploit the vulnerability.

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.

Memory leak in Xen 3.3 through 4.8.x allows guest OS users to cause a denial of service (ARM or x86 AMD host OS memory consumption) by continually rebooting, because certain cleanup is skipped if no pass-through device was ever assigned, aka XSA-207.

An issue was discovered in Xen through 4.14.x. Xenstored and guests communicate via a shared memory page using a specific protocol. When a guest violates this protocol, xenstored will drop the connection to that guest. Unfortunately, this is done by just removing the guest from xenstored's internal management, resulting in the same actions as if the guest had been destroyed, including sending an @releaseDomain event. @releaseDomain events do not say that the guest has been removed. All watchers of this event must look at the states of all guests to find the guest that has been removed. When an @releaseDomain is generated due to a domain xenstored protocol violation, because the guest is still running, the watchers will not react. Later, when the guest is actually destroyed, xenstored will no longer have it stored in its internal data base, so no further @releaseDomain event will be sent. This can lead to a zombie domain; memory mappings of that guest's memory will not be removed, due to the missing event. This zombie domain will be cleaned up only after another domain is destroyed, as that will trigger another @releaseDomain event. If the device model of the guest that violated the Xenstore protocol is running in a stub-domain, a use-after-free case could happen in xenstored, after having removed the guest from its internal data base, possibly resulting in a crash of xenstored. A malicious guest can block resources of the host for a period after its own death. Guests with a stub domain device model can eventually crash xenstored, resulting in a more serious denial of service (the prevention of any further domain management operations). Only the C variant of Xenstore is affected; the Ocaml variant is not affected. Only HVM guests with a stubdom device model can cause a serious DoS.

Xen through 4.7.x allows local ARM guest OS users to cause a denial of service (host panic) by sending an asynchronous abort.

Xen through 4.7.x allows local ARM guest OS users to cause a denial of service (host crash) via vectors involving an asynchronous abort while at HYP.

Xen and the Linux kernel through 4.5.x do not properly suppress hugetlbfs support in x86 PV guests, which allows local PV guest OS users to cause a denial of service (guest OS crash) by attempting to access a hugetlbfs mapped area.

Xen 4.6.x and earlier allows local guest administrators to cause a denial of service (host reboot) via vectors related to multiple mappings of MMIO pages with different cachability settings.

The ntpd client in NTP 4.x before 4.2.8p4 and 4.3.x before 4.3.77 allows remote attackers to cause a denial of service via a number of crafted "KOD" messages.

The rate limiting feature in NTP 4.x before 4.2.8p4 and 4.3.x before 4.3.77 allows remote attackers to have unspecified impact via a large number of crafted requests.

The PCI backend driver in Xen, when running on an x86 system and using Linux 3.1.x through 4.3.x as the driver domain, allows local guest administrators to generate a continuous stream of WARN messages and cause a denial of service (disk consumption) by leveraging a system with access to a passed-through MSI or MSI-X capable physical PCI device and XEN_PCI_OP_enable_msi operations, aka "Linux pciback missing sanity checks."

The mod_l2_entry function in arch/x86/mm.c in Xen 3.4 through 4.6.x does not properly validate level 2 page table entries, which allows local PV guest administrators to gain privileges via a crafted superpage mapping.

The do_mmu_update function in arch/x86/mm.c in Xen 4.x through 4.4.x does not properly restrict updates to only PV page tables, which allows remote PV guests to cause a denial of service (NULL pointer dereference) by leveraging hardware emulation services for HVM guests using Hardware Assisted Paging (HAP).

The do_mmu_update function in arch/x86/mm.c in Xen 3.2.x through 4.4.x does not properly manage page references, which allows remote domains to cause a denial of service by leveraging control over an HVM guest and a crafted MMU_MACHPHYS_UPDATE.

The ARM image loading functionality in Xen 4.4.x does not properly validate kernel length, which allows local users to read system memory or cause a denial of service (crash) via a crafted 32-bit ARM guest kernel in an image, which triggers a buffer overflow.

Xen 4.4.x does not properly validate the load address for 64-bit ARM guest kernels, which allows local users to read system memory or cause a denial of service (crash) via a crafted kernel, which triggers a buffer overflow.

The vgic_distr_mmio_write function in the virtual guest interrupt controller (GIC) distributor (arch/arm/vgic.c) in Xen 4.4.x, when running on an ARM system, allows local guest users to cause a denial of service (NULL pointer dereference and host crash) via unspecified vectors.

The (1) do_send and (2) do_recv functions in io.c in libvchan in Xen 4.2.x, 4.3.x, and 4.4-RC series allows local guests to cause a denial of service or possibly gain privileges via crafted xenstore ring indexes, which triggers a "read or write past the end of the ring."

Citrix NetScaler Application Delivery Controller (ADC) 10.0 before 10.0-76.7 allows remote attackers to cause a denial of service (nsconfigd crash and appliance reboot) via a crafted request.

Xen 4.2.x and 4.3.x, when nested virtualization is disabled, does not properly check the emulation paths for (1) VMLAUNCH and (2) VMRESUME, which allows local HVM guest users to cause a denial of service (host crash) via unspecified vectors related to "guest VMX instruction execution."

Xen before 4.1.x, 4.2.x, and 4.3.x does not take the page_alloc_lock and grant_table.lock in the same order, which allows local guest administrators with access to multiple vcpus to cause a denial of service (host deadlock) via unspecified vectors.

NVIDIA vGPU driver contains a vulnerability in the Virtual GPU Manager (vGPU plugin), where there is the potential to write to a shared memory location and manipulate the data after the data has been validated, which may lead to denial of service and escalation of privileges and information disclosure but attacker doesn't have control over what information is obtained. This affects vGPU version 12.x (prior to 12.2), version 11.x (prior to 11.4) and version 8.x (prior to 8.7).

NVIDIA vGPU manager contains a vulnerability in the vGPU plugin, in which input data is not validated, which may lead to unexpected consumption of resources, which in turn may lead to denial of service. This affects vGPU version 8.x (prior to 8.6) and version 11.0 (prior to 11.3).

NVIDIA vGPU software contains a vulnerability in the guest kernel mode driver and vGPU plugin, in which an input index is not validated, which may lead to tampering of data or denial of service. This affects vGPU version 8.x (prior to 8.6) and version 11.0 (prior to 11.3).

NVIDIA vGPU manager contains a vulnerability in the vGPU plugin, in which input data is not validated, which may lead to tampering of data or denial of service. This affects vGPU version 8.x (prior to 8.6) and version 11.0 (prior to 11.3).

NVIDIA vGPU driver contains a vulnerability in the guest kernel mode driver and Virtual GPU Manager (vGPU plugin), in which an input length is not validated, which may lead to information disclosure, tampering of data or denial of service. This affects vGPU version 12.x (prior to 12.2) and version 11.x (prior to 11.4).

NVIDIA vGPU software contains a vulnerability in the Virtual GPU Manager (vGPU plugin), in which certain input data is not validated, which may lead to information disclosure, tampering of data, or denial of service. This affects vGPU version 12.x (prior to 12.2), version 11.x (prior to 11.4) and version 8.x (prior 8.7).

Xen 3.1 through 4.x, when running 64-bit hosts on Intel CPUs, does not clear the NT flag when using an IRET after a SYSENTER instruction, which allows PV guest users to cause a denial of service (hypervisor crash) by triggering a #GP fault, which is not properly handled by another IRET instruction.

The (1) tmemc_save_get_next_page and (2) tmemc_save_get_next_inv functions and the (3) TMEMC_SAVE_GET_POOL_UUID sub-operation in the Transcendent Memory (TMEM) in Xen 4.0, 4.1, and 4.2 "do not check incoming guest output buffer pointers," which allows local guest OS users to cause a denial of service (memory corruption and host crash) or execute arbitrary code via unspecified vectors. NOTE: this issue was originally published as part of CVE-2012-3497, which was too general; CVE-2012-3497 has been SPLIT into this ID and others.

The do_tmem_destroy_pool function in the Transcendent Memory (TMEM) in Xen 4.0, 4.1, and 4.2 does not properly validate pool ids, which allows local guest OS users to cause a denial of service (memory corruption and host crash) or execute arbitrary code via unspecified vectors. NOTE: this issue was originally published as part of CVE-2012-3497, which was too general; CVE-2012-3497 has been SPLIT into this ID and others.

Xen 4.4.x does not properly check alignment, which allows local users to cause a denial of service (crash) via an unspecified field in a DTB header in a 32-bit guest kernel.

The XENMEM_exchange handler in Xen 4.2 and earlier does not properly check the memory address, which allows local PV guest OS administrators to cause a denial of service (crash) or possibly gain privileges via unspecified vectors that overwrite memory in the hypervisor reserved range.

The do_tmem_op function in the Transcendent Memory (TMEM) in Xen 4.0, 4.1, and 4.2 allow local guest OS users to cause a denial of service (host crash) and possibly have other unspecified impacts via unspecified vectors related to "broken locking checks" in an "error path." NOTE: this issue was originally published as part of CVE-2012-3497, which was too general; CVE-2012-3497 has been SPLIT into this ID and others.

Citrix XenApp Online Plug-in for Windows 12.1 and earlier, and Citrix Receiver for Windows 3.2 and earlier could allow remote attackers to execute arbitrary code by convincing a target to open a specially crafted file from an SMB or WebDAV fileserver.

The PV domain builder in Xen 4.2 and earlier does not validate the size of the kernel or ramdisk (1) before or (2) after decompression, which allows local guest administrators to cause a denial of service (domain 0 memory consumption) via a crafted (a) kernel or (b) ramdisk.

Qemu, as used in Xen 4.0, 4.1 and possibly other products, when emulating certain devices with a virtual console backend, allows local OS guest users to gain privileges via a crafted escape VT100 sequence that triggers the overwrite of a "device model's address space."

(1) TMEMC_SAVE_GET_CLIENT_WEIGHT, (2) TMEMC_SAVE_GET_CLIENT_CAP, (3) TMEMC_SAVE_GET_CLIENT_FLAGS and (4) TMEMC_SAVE_END in the Transcendent Memory (TMEM) in Xen 4.0, 4.1, and 4.2 allow local guest OS users to cause a denial of service (NULL pointer dereference or memory corruption and host crash) or possibly have other unspecified impacts via a NULL client id.

PHYSDEVOP_map_pirq in Xen 4.1 and 4.2 and Citrix XenServer 6.0.2 and earlier allows local HVM guest OS kernels to cause a denial of service (host crash) and possibly read hypervisor or guest memory via vectors related to a missing range check of map->index.

The physdev_get_free_pirq hypercall in arch/x86/physdev.c in Xen 4.1.x and Citrix XenServer 6.0.2 and earlier uses the return value of the get_free_pirq function as an array index without checking that the return value indicates an error, which allows guest OS users to cause a denial of service (invalid memory write and host crash) and possibly gain privileges via unspecified vectors.