CVE-2016-4440

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2016-06-27 · updated 2026-06-17
Weakness: CWE-264

Description

arch/x86/kvm/vmx.c in the Linux kernel through 4.6.3 mishandles the APICv on/off state, which allows guest OS users to obtain direct APIC MSR access on the host OS, and consequently cause a denial of service (host OS crash) or possibly execute arbitrary code on the host OS, via x2APIC mode.

Affected products

Linux kernel: from 4.5 before 4.7 — fixed in 4.7

How to fix

Upgrade to a fixed version: Linux kernel 4.7. Check the vendor advisory for mitigations.

References

http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=3ce424e45411cf5a13105e0386b6ecf6eeb4f66f
http://www.openwall.com/lists/oss-security/2016/05/20/2
https://bugzilla.redhat.com/show_bug.cgi?id=1337806
https://github.com/torvalds/linux/commit/3ce424e45411cf5a13105e0386b6ecf6eeb4f66f
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=3ce424e45411cf5a13105e0386b6ecf6eeb4f66f
http://www.openwall.com/lists/oss-security/2016/05/20/2
https://bugzilla.redhat.com/show_bug.cgi?id=1337806
https://github.com/torvalds/linux/commit/3ce424e45411cf5a13105e0386b6ecf6eeb4f66f

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