Citrix Hypervisor Security Update

Description of Problem Two issues have been identified in Citrix Hypervisor that may, if exploited, allow privileged code in an HVM guest VM to compromise or crash the host. These issues only apply in specific configurations; furthermore, Citrix believes that there would be significant difficulty...

CVE-2020-27672

A race condition flaw was found in the Xen code responsible for handling the updating of the hypervisor's own page tables. This flaw allows a malicious guest to cause a denial of service, host data corruption, or potential privilege escalation. The highest threat from this vulnerability is to...

Xen Migrating Timers Race condition DoS (XSA-336)

According to its self-reported version number, the Xen hypervisor installed on the remote host is affected by a denial of service DoS vulnerability. When migrating timers of x86 HVM guests between its vCPU-s, the locking model used allows for a second vCPU of the same guest also operating on the...

CVE-2020-27671

CVE-2020-27671 affects Xen 4.14.x and earlier on x86 HVM/PVH guests. The issue arises from mishandling coalescing of per-page IOMMU TLB flushes in the Xen IOMMU path, enabling a guest OS user to cause denial of service (data corruption), data leaks, or potentially a privilege escalation. Connecte...

CVE-2020-27671: Undefined Security Weakness

An issue was discovered in Xen through 4.14.x allowing x86 HVM and PVH guest OS users to cause a denial of service data corruption, cause a data leak, or possibly gain privileges because coalescing of per-page IOMMU TLB flushes is mishandled...

undue deferral of IOMMU TLB flushes

ISSUE DESCRIPTION To efficiently change the physical to machine address mappings of a larger range of addresses for fully virtualized guests, Xen contains an optimization to coalesce per-page IOMMU TLB flushes into a single, wider flush after all adjustments have been made. While this is fine to ...

x86: Race condition in Xen mapping code

ISSUE DESCRIPTION The Xen code handling the updating of the hypervisor's own pagetables tries to use 2MiB and 1GiB superpages as much as possible to maximize TLB efficiency. Some of the operations for checking and coalescing superpages take non-negligible amount of time; to avoid potential lock...

Fedora 31 : xen (2020-d46fe34349)

x86 pv: Crash when handling guest access to MSRMISCENABLE XSA-333, CVE-2020-25602 1881619 Missing unlock in XENMEMacquireresource error path XSA-334, CVE-2020-25598 1881616 race when migrating timers between x86 HVM vCPU-s XSA-336, CVE-2020-25604 1881618 PCI passthrough code reading back hardware...

Denial Of Service (DoS)

xen is vulnerable to denial of saervice. A race condition when migrating timers between x86 HVM vCPUs allows an attacker to cause a deadlock in the application which will result in a hang or application crash...

ALPINE-CVE-2020-25604

An issue was discovered in Xen through 4.14.x. There is a race condition when migrating timers between x86 HVM vCPUs. When migrating timers of x86 HVM guests between its vCPUs, the locking model used allows for a second vCPU of the same guest also operating on the timers to release a lock that it...

CVE-2020-25604

An issue was discovered in Xen through 4.14.x. There is a race condition when migrating timers between x86 HVM vCPUs. When migrating timers of x86 HVM guests between its vCPUs, the locking model used allows for a second vCPU of the same guest also operating on the timers to release a lock that it...

CVE-2020-25598

An issue was discovered in Xen 4.14.x. There is a missing unlock in the XENMEMacquireresource error path. The RCU Read, Copy, Update mechanism is a synchronisation primitive. A buggy error path in the XENMEMacquireresource exits without releasing an RCU reference, which is conceptually similar to...

CVE-2020-25598

An issue was discovered in Xen 4.14.x. There is a missing unlock in the XENMEMacquireresource error path. The RCU Read, Copy, Update mechanism is a synchronisation primitive. A buggy error path in the XENMEMacquireresource exits without releasing an RCU reference, which is conceptually similar to...

CVE-2020-25604

An issue was discovered in Xen through 4.14.x. There is a race condition when migrating timers between x86 HVM vCPUs. When migrating timers of x86 HVM guests between its vCPUs, the locking model used allows for a second vCPU of the same guest also operating on the timers to release a lock that it...

DEBIAN-CVE-2020-25604

An issue was discovered in Xen through 4.14.x. There is a race condition when migrating timers between x86 HVM vCPUs. When migrating timers of x86 HVM guests between its vCPUs, the locking model used allows for a second vCPU of the same guest also operating on the timers to release a lock that it...

Design/Logic Flaw

An issue was discovered in Xen 4.14.x. There is a missing unlock in the XENMEMacquireresource error path. The RCU Read, Copy, Update mechanism is a synchronisation primitive. A buggy error path in the XENMEMacquireresource exits without releasing an RCU reference, which is conceptually similar to...

CVE-2020-25598

An issue was discovered in Xen 4.14.x. There is a missing unlock in the XENMEMacquireresource error path. The RCU Read, Copy, Update mechanism is a synchronisation primitive. A buggy error path in the XENMEMacquireresource exits without releasing an RCU reference, which is conceptually similar to...

Race condition

An issue was discovered in Xen through 4.14.x. There is a race condition when migrating timers between x86 HVM vCPUs. When migrating timers of x86 HVM guests between its vCPUs, the locking model used allows for a second vCPU of the same guest also operating on the timers to release a lock that it...

CVE-2020-25604

An issue was discovered in Xen through 4.14.x. There is a race condition when migrating timers between x86 HVM vCPUs. When migrating timers of x86 HVM guests between its vCPUs, the locking model used allows for a second vCPU of the same guest also operating on the timers to release a lock that it...

CVE-2020-25604

CVE-2020-25604 in Xen up to 4.14.x describes a race condition when migrating timers between x86 HVM vCPUs. The locking model can allow a second vCPU of the same guest to release a lock it did not acquire, potentially causing a hang or crash (DoS) of the hypervisor. Affected: all Xen versions on x...