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CVE-2019-7221

Published: 21 March 2019

The KVM implementation in the Linux kernel through 4.20.5 has a Use-after-Free.

From the Ubuntu Security Team

Jim Mattson and Felix Wilhelm discovered a use-after-free vulnerability in the KVM subsystem of the Linux kernel, when using nested virtual machines. A local attacker in a guest VM could use this to cause a denial of service (system crash) or possibly execute arbitrary code in the host system.

Notes

AuthorNote
tyhicks
Ubuntu kernels do not enable nested KVM virtualization by default and
are unaffected by this flaw in the default configuration. However, installing
QEMU results in nested KVM support to be enabled via the
/etc/modprobe.d/qemu-system-x86.conf file. To ensure that nested
virtualization is not enabled, verify that the
/sys/module/kvm_intel/parameters/nested file contains "N".

Priority

Medium

Cvss 3 Severity Score

7.8

Score breakdown

Status

Package Release Status
linux
Launchpad, Ubuntu, Debian
bionic
Released (4.15.0-47.50)
cosmic
Released (4.18.0-17.18)
disco Not vulnerable
(5.0.0-7.8)
trusty Not vulnerable
(3.11.0-12.19)
upstream
Released (5.0~rc6)
xenial
Released (4.4.0-145.171)
Patches:
Introduced by

f4124500c2c13eb1208c6143b3f6d469709dea10

Fixed by ecec76885bcfe3294685dc363fd1273df0d5d65f
linux-goldfish
Launchpad, Ubuntu, Debian
bionic Does not exist

cosmic Does not exist

disco Does not exist

trusty Does not exist
(trusty was ignored [abandoned])
upstream
Released (5.0~rc6)
xenial Ignored
(end of life)
linux-aws
Launchpad, Ubuntu, Debian
bionic
Released (4.15.0-1035.37)
cosmic
Released (4.18.0-1012.14)
disco Not vulnerable
(5.0.0-1001.1)
trusty
Released (4.4.0-1040.43)
upstream
Released (5.0~rc6)
xenial
Released (4.4.0-1079.89)
linux-flo
Launchpad, Ubuntu, Debian
bionic Does not exist

cosmic Does not exist

disco Does not exist

trusty Does not exist
(trusty was ignored [abandoned])
upstream
Released (5.0~rc6)
xenial Ignored
(abandoned)
linux-aws-hwe
Launchpad, Ubuntu, Debian
bionic Does not exist

cosmic Does not exist

disco Does not exist

trusty Does not exist

upstream
Released (5.0~rc6)
xenial
Released (4.15.0-1035.37~16.04.1)
linux-azure
Launchpad, Ubuntu, Debian
bionic
Released (4.18.0-1014.14~18.04.1)
cosmic
Released (4.18.0-1014.14)
disco Not vulnerable
(5.0.0-1001.1)
trusty
Released (4.15.0-1041.45~14.04.1)
upstream
Released (5.0~rc6)
xenial
Released (4.15.0-1041.45)
linux-azure-edge
Launchpad, Ubuntu, Debian
bionic
Released (4.18.0-1014.14~18.04.1)
cosmic Does not exist

disco Does not exist

trusty Does not exist

upstream
Released (5.0~rc6)
xenial
Released (4.15.0-1041.45)
linux-euclid
Launchpad, Ubuntu, Debian
bionic Does not exist

cosmic Does not exist

disco Does not exist

trusty Does not exist

upstream
Released (5.0~rc6)
xenial Ignored
(was needed ESM criteria)
linux-gcp
Launchpad, Ubuntu, Debian
bionic
Released (4.15.0-1029.31)
cosmic
Released (4.18.0-1008.9)
disco Not vulnerable
(5.0.0-1001.1)
trusty Does not exist

upstream
Released (5.0~rc6)
xenial
Released (4.15.0-1029.31~16.04.1)
linux-gcp-edge
Launchpad, Ubuntu, Debian
bionic
Released (4.18.0-1008.9~18.04.1)
cosmic Does not exist

disco Does not exist

trusty Does not exist

upstream
Released (5.0~rc6)
xenial Does not exist

linux-gke
Launchpad, Ubuntu, Debian
bionic Not vulnerable

cosmic Does not exist

disco Does not exist

trusty Does not exist

upstream
Released (5.0~rc6)
xenial Ignored
(end of standard support)
linux-grouper
Launchpad, Ubuntu, Debian
bionic Does not exist

cosmic Does not exist

disco Does not exist

trusty Does not exist
(trusty was ignored [abandoned])
upstream
Released (5.0~rc6)
xenial Does not exist

linux-hwe
Launchpad, Ubuntu, Debian
bionic
Released (4.18.0-17.18~18.04.1)
cosmic Does not exist

disco Does not exist

trusty Does not exist

upstream
Released (5.0~rc6)
xenial
Released (4.15.0-47.50~16.04.1)
linux-hwe-edge
Launchpad, Ubuntu, Debian
bionic Not vulnerable
(5.0.0-15.16~18.04.1)
cosmic Does not exist

disco Does not exist

trusty Does not exist

upstream
Released (5.0~rc6)
xenial
Released (4.15.0-47.50~16.04.1)
linux-kvm
Launchpad, Ubuntu, Debian
bionic
Released (4.15.0-1031.31)
cosmic
Released (4.18.0-1009.9)
disco Not vulnerable
(5.0.0-1001.1)
trusty Does not exist

upstream
Released (5.0~rc6)
xenial
Released (4.4.0-1043.49)
linux-lts-trusty
Launchpad, Ubuntu, Debian
bionic Does not exist

cosmic Does not exist

disco Does not exist

trusty Does not exist

upstream
Released (5.0~rc6)
xenial Does not exist

linux-lts-utopic
Launchpad, Ubuntu, Debian
bionic Does not exist

cosmic Does not exist

disco Does not exist

trusty Ignored
(end of life, was ignored)
upstream
Released (5.0~rc6)
xenial Does not exist

linux-lts-vivid
Launchpad, Ubuntu, Debian
bionic Does not exist

cosmic Does not exist

disco Does not exist

trusty Ignored
(end of life, was ignored)
upstream
Released (5.0~rc6)
xenial Does not exist

linux-lts-wily
Launchpad, Ubuntu, Debian
bionic Does not exist

cosmic Does not exist

disco Does not exist

trusty Ignored
(end of life, was ignored)
upstream
Released (5.0~rc6)
xenial Does not exist

linux-lts-xenial
Launchpad, Ubuntu, Debian
bionic Does not exist

cosmic Does not exist

disco Does not exist

trusty
Released (4.4.0-144.170~14.04.1)
upstream
Released (5.0~rc6)
xenial Does not exist

linux-maguro
Launchpad, Ubuntu, Debian
bionic Does not exist

cosmic Does not exist

disco Does not exist

trusty Does not exist
(trusty was ignored [abandoned])
upstream
Released (5.0~rc6)
xenial Does not exist

linux-mako
Launchpad, Ubuntu, Debian
bionic Does not exist

cosmic Does not exist

disco Does not exist

trusty Does not exist
(trusty was ignored [abandoned])
upstream
Released (5.0~rc6)
xenial Ignored
(abandoned)
linux-manta
Launchpad, Ubuntu, Debian
bionic Does not exist

cosmic Does not exist

disco Does not exist

trusty Does not exist
(trusty was ignored [abandoned])
upstream
Released (5.0~rc6)
xenial Does not exist

linux-oem
Launchpad, Ubuntu, Debian
bionic
Released (4.15.0-1035.40)
cosmic
Released (4.15.0-1035.40)
disco Not vulnerable
(4.15.0-1035.40)
trusty Does not exist

upstream
Released (5.0~rc6)
xenial Ignored
(end of standard support, was needs-triage)
linux-oracle
Launchpad, Ubuntu, Debian
bionic
Released (4.15.0-1010.12)
cosmic
Released (4.15.0-1010.12)
disco Not vulnerable
(4.15.0-1010.12)
trusty Does not exist

upstream
Released (5.0~rc6)
xenial
Released (4.15.0-1010.12~16.04.1)
linux-raspi2
Launchpad, Ubuntu, Debian
bionic
Released (4.15.0-1033.35)
cosmic
Released (4.18.0-1011.13)
disco Not vulnerable
(5.0.0-1004.4)
trusty Does not exist

upstream
Released (5.0~rc6)
xenial
Released (4.4.0-1106.114)
linux-snapdragon
Launchpad, Ubuntu, Debian
bionic
Released (4.15.0-1053.57)
cosmic Does not exist

disco Not vulnerable
(5.0.0-1010.10)
trusty Does not exist

upstream
Released (5.0~rc6)
xenial
Released (4.4.0-1110.115)

Severity score breakdown

Parameter Value
Base score 7.8
Attack vector Local
Attack complexity Low
Privileges required Low
User interaction None
Scope Unchanged
Confidentiality High
Integrity impact High
Availability impact High
Vector CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H