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CVE-2019-18424

Published: 31 October 2019

An issue was discovered in Xen through 4.12.x allowing attackers to gain host OS privileges via DMA in a situation where an untrusted domain has access to a physical device. This occurs because passed through PCI devices may corrupt host memory after deassignment. When a PCI device is assigned to an untrusted domain, it is possible for that domain to program the device to DMA to an arbitrary address. The IOMMU is used to protect the host from malicious DMA by making sure that the device addresses can only target memory assigned to the guest. However, when the guest domain is torn down, or the device is deassigned, the device is assigned back to dom0, thus allowing any in-flight DMA to potentially target critical host data. An untrusted domain with access to a physical device can DMA into host memory, leading to privilege escalation. Only systems where guests are given direct access to physical devices capable of DMA (PCI pass-through) are vulnerable. Systems which do not use PCI pass-through are not vulnerable.

Notes

AuthorNote
mdeslaur
hypervisor packages are in universe. For
issues in the hypervisor, add appropriate
tags to each section, ex:
Tags_xen: universe-binary

Priority

Medium

Cvss 3 Severity Score

6.8

Score breakdown

Status

Package Release Status
xen
Launchpad, Ubuntu, Debian
bionic Needed

disco Ignored
(end of life)
eoan Ignored
(end of life)
focal Not vulnerable
(4.11.3+24-g14b62ab3e5-1ubuntu1)
groovy Not vulnerable
(4.11.3+24-g14b62ab3e5-1ubuntu1)
hirsute Not vulnerable
(4.11.3+24-g14b62ab3e5-1ubuntu1)
impish Not vulnerable
(4.11.3+24-g14b62ab3e5-1ubuntu1)
jammy Not vulnerable
(4.11.3+24-g14b62ab3e5-1ubuntu1)
kinetic Not vulnerable
(4.11.3+24-g14b62ab3e5-1ubuntu1)
lunar Not vulnerable
(4.11.3+24-g14b62ab3e5-1ubuntu1)
mantic Not vulnerable
(4.11.3+24-g14b62ab3e5-1ubuntu1)
noble Not vulnerable
(4.11.3+24-g14b62ab3e5-1ubuntu1)
trusty Does not exist

upstream Needs triage

xenial Needed

Binaries built from this source package are in Universe and so are supported by the community.

Severity score breakdown

Parameter Value
Base score 6.8
Attack vector Physical
Attack complexity Low
Privileges required None
User interaction None
Scope Unchanged
Confidentiality High
Integrity impact High
Availability impact High
Vector CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H