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CVE-2018-12904

Published: 27 June 2018

In arch/x86/kvm/vmx.c in the Linux kernel before 4.17.2, when nested virtualization is used, local attackers could cause L1 KVM guests to VMEXIT, potentially allowing privilege escalations and denial of service attacks due to lack of checking of CPL.

From the Ubuntu Security Team

Felix Wilhelm discovered that the KVM implementation in the Linux kernel did not properly perform permission checks in some situations when nested virtualization is used. An attacker in a guest VM could possibly use this to escape into an outer VM or the host OS.

Notes

AuthorNote
tyhicks
Ubuntu kernels do not enable nested KVM virtualization by default and
are unaffected by this flaw in the default configuration. To ensure that
nested virtualization is not enabled, verify that the
/sys/module/kvm_intel/parameters/nested file contains "N".

Priority

Low

Cvss 3 Severity Score

4.9

Score breakdown

Status

Package Release Status
linux
Launchpad, Ubuntu, Debian
artful Ignored
(end of life)
trusty Not vulnerable

bionic
Released (4.15.0-33.36)
cosmic Not vulnerable
(4.17.0-6.7)
upstream
Released (4.18~rc1)
xenial Not vulnerable

Patches:
Introduced by

70f3aac964ae2bc9a0a1d5d65a62e258591ade18

Fixed by 727ba748e110b4de50d142edca9d6a9b7e6111d8
linux-aws
Launchpad, Ubuntu, Debian
artful Does not exist

bionic
Released (4.15.0-1020.20)
cosmic Not vulnerable
(4.15.0-1020.20)
trusty Not vulnerable

upstream
Released (4.18~rc1)
xenial Not vulnerable

linux-azure
Launchpad, Ubuntu, Debian
artful Does not exist

bionic
Released (4.15.0-1022.23)
cosmic Not vulnerable
(4.18.0-1003.3)
upstream
Released (4.18~rc1)
trusty Not vulnerable
(4.15.0-1023.24~14.04.1)
xenial
Released (4.15.0-1022.22~16.04.1)
linux-azure-edge
Launchpad, Ubuntu, Debian
artful Does not exist

bionic Not vulnerable
(4.18.0-1003.3~18.04.1)
cosmic Does not exist

trusty Does not exist

upstream
Released (4.18~rc1)
xenial
Released (4.15.0-1022.23)
linux-euclid
Launchpad, Ubuntu, Debian
artful Does not exist

bionic Does not exist

cosmic Does not exist

trusty Does not exist

upstream
Released (4.18~rc1)
xenial Not vulnerable

linux-flo
Launchpad, Ubuntu, Debian
artful Does not exist

bionic Does not exist

cosmic Does not exist

trusty Does not exist
(trusty was ignored [abandoned])
upstream
Released (4.18~rc1)
xenial Ignored
(abandoned)
linux-gcp
Launchpad, Ubuntu, Debian
artful Does not exist

bionic
Released (4.15.0-1018.19)
cosmic Not vulnerable
(4.15.0-1018.19)
trusty Does not exist

upstream
Released (4.18~rc1)
xenial
Released (4.15.0-1018.19~16.04.2)
linux-gke
Launchpad, Ubuntu, Debian
artful Does not exist

bionic Does not exist

cosmic Does not exist

trusty Does not exist

upstream
Released (4.18~rc1)
xenial Ignored
(end of standard support)
linux-goldfish
Launchpad, Ubuntu, Debian
artful Does not exist

bionic Does not exist

cosmic Does not exist

trusty Does not exist
(trusty was ignored [abandoned])
upstream
Released (4.18~rc1)
xenial Ignored
(end of life)
linux-grouper
Launchpad, Ubuntu, Debian
artful Does not exist

bionic Does not exist

cosmic Does not exist

trusty Does not exist
(trusty was ignored [abandoned])
upstream
Released (4.18~rc1)
xenial Does not exist

linux-hwe
Launchpad, Ubuntu, Debian
artful Does not exist

bionic Not vulnerable

cosmic Does not exist

trusty Does not exist

upstream
Released (4.18~rc1)
xenial
Released (4.15.0-33.36~16.04.1)
linux-hwe-edge
Launchpad, Ubuntu, Debian
artful Does not exist

bionic Not vulnerable
(4.18.0-11.12~18.04.1)
cosmic Does not exist

trusty Does not exist

upstream
Released (4.18~rc1)
xenial
Released (4.15.0-33.36~16.04.1)
linux-kvm
Launchpad, Ubuntu, Debian
artful Does not exist

bionic
Released (4.15.0-1020.20)
cosmic Not vulnerable
(4.15.0-1020.20)
trusty Does not exist

upstream
Released (4.18~rc1)
xenial Not vulnerable

linux-lts-trusty
Launchpad, Ubuntu, Debian
artful Does not exist

bionic Does not exist

cosmic Does not exist

trusty Does not exist

upstream
Released (4.18~rc1)
xenial Does not exist

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

bionic Does not exist

cosmic Does not exist

trusty Does not exist
(trusty was ignored [end of standard support])
upstream
Released (4.18~rc1)
xenial Does not exist

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

bionic Does not exist

cosmic Does not exist

trusty Does not exist
(trusty was ignored [end of standard support])
upstream
Released (4.18~rc1)
xenial Does not exist

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

bionic Does not exist

cosmic Does not exist

trusty Does not exist
(trusty was ignored [end of standard support])
upstream
Released (4.18~rc1)
xenial Does not exist

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

bionic Does not exist

cosmic Does not exist

trusty Not vulnerable

upstream
Released (4.18~rc1)
xenial Does not exist

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

bionic Does not exist

cosmic Does not exist

trusty Does not exist
(trusty was ignored [abandoned])
upstream
Released (4.18~rc1)
xenial Does not exist

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

bionic Does not exist

cosmic Does not exist

trusty Does not exist
(trusty was ignored [abandoned])
upstream
Released (4.18~rc1)
xenial Ignored
(abandoned)
linux-manta
Launchpad, Ubuntu, Debian
artful Does not exist

bionic Does not exist

cosmic Does not exist

trusty Does not exist
(trusty was ignored [abandoned])
upstream
Released (4.18~rc1)
xenial Does not exist

linux-oem
Launchpad, Ubuntu, Debian
artful Does not exist

bionic
Released (4.15.0-1017.20)
cosmic Not vulnerable
(4.15.0-1017.20)
trusty Does not exist

upstream
Released (4.18~rc1)
xenial Ignored
(end of standard support, was needed)
linux-raspi2
Launchpad, Ubuntu, Debian
artful Ignored
(end of life)
bionic
Released (4.15.0-1021.23)
cosmic Not vulnerable
(4.15.0-1021.23)
trusty Does not exist

upstream
Released (4.18~rc1)
xenial Not vulnerable

linux-snapdragon
Launchpad, Ubuntu, Debian
artful Not vulnerable

bionic Not vulnerable

cosmic Does not exist

trusty Does not exist

upstream
Released (4.18~rc1)
xenial Not vulnerable

Severity score breakdown

Parameter Value
Base score 4.9
Attack vector Local
Attack complexity High
Privileges required None
User interaction None
Scope Unchanged
Confidentiality Low
Integrity impact Low
Availability impact Low
Vector CVSS:3.0/AV:L/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L