CVE-2019-18424

NameCVE-2019-18424
DescriptionAn 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.
SourceCVE (at NVD; CERT, LWN, oss-sec, fulldisc, bugtraq, EDB, Metasploit, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, Mageia, GitHub code/issues, web search, more)
ReferencesDSA-4602-1
NVD severitymedium
Debian Bugs947944

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
xen (PTS)stretch (security), stretch4.8.5.final+shim4.10.4-1+deb9u12fixed
buster4.11.3+24-g14b62ab3e5-1~deb10u1fixed
buster (security)4.11.4+24-gddaaccbbab-1~deb10u1fixed
bullseye, sid4.11.4+24-gddaaccbbab-1fixed

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
xensource(unstable)4.11.3+24-g14b62ab3e5-1947944
xensourcebuster4.11.3+24-g14b62ab3e5-1~deb10u1DSA-4602-1
xensourcejessie(unfixed)end-of-life
xensourcestretch4.8.5.final+shim4.10.4-1+deb9u12DSA-4602-1

Notes

[jessie] - xen <end-of-life> (Not supported in jessie LTS)
https://xenbits.xen.org/xsa/advisory-302.html

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