{"id":"CVE-2016-4020","url":"https://www.cyber-defence.io/tools/cve/CVE-2016-4020","generatedAt":"2026-10-27T17:56:59.491Z","title":"The patch_instruction function in hw/i386/kvmvapic.c in QEMU does not initialize the imm32 variable, which allows local guest OS administrators to obtain sensitive information from host stack memory by accessing the Task Priority Register (TPR).","description":"The patch_instruction function in hw/i386/kvmvapic.c in QEMU does not initialize the imm32 variable, which allows local guest OS administrators to obtain sensitive information from host stack memory by accessing the Task Priority Register (TPR).","published":"2016-05-25T15:59:05.000Z","lastModified":"2026-06-17T00:46:45.000Z","status":"Modified","sourceIdentifier":"secalert@redhat.com","cvss":{"version":"3.1","score":6.5,"severity":"MEDIUM","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N"},"cwe":[],"affected":["qemu/qemu","canonical/ubuntu linux","debian/debian linux","redhat/openstack","redhat/enterprise linux desktop","redhat/enterprise linux eus","redhat/enterprise linux server","redhat/enterprise linux server aus","redhat/enterprise linux server tus","redhat/enterprise linux workstation","redhat/virtualization"],"epss":{"score":0.00372,"percentile":0.30931,"date":"2026-10-26","history":[]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"low","text":"Lower severity and a low EPSS score (0.37%). Track it; it rarely justifies an emergency change on its own."},"changes":[],"references":[{"url":"http://git.qemu.org/?p=qemu.git%3Ba=commit%3Bh=691a02e2ce0c413236a78dee6f2651c937b09fb0","source":"secalert@redhat.com"},{"url":"http://www.securityfocus.com/bid/86067","tags":["Third Party Advisory","VDB Entry"],"source":"secalert@redhat.com"},{"url":"http://www.ubuntu.com/usn/USN-2974-1","tags":["Third Party Advisory"],"source":"secalert@redhat.com"},{"url":"https://access.redhat.com/errata/RHSA-2017:1856","tags":["Third Party Advisory"],"source":"secalert@redhat.com"},{"url":"https://access.redhat.com/errata/RHSA-2017:2392","tags":["Third Party Advisory"],"source":"secalert@redhat.com"},{"url":"https://access.redhat.com/errata/RHSA-2017:2408","tags":["Third Party Advisory"],"source":"secalert@redhat.com"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=1313686","tags":["Issue Tracking","Third Party Advisory"],"source":"secalert@redhat.com"},{"url":"https://lists.debian.org/debian-lts-announce/2018/11/msg00038.html","tags":["Mailing List","Third Party Advisory"],"source":"secalert@redhat.com"},{"url":"https://lists.gnu.org/archive/html/qemu-devel/2016-04/msg01106.html","tags":["Patch","Third Party Advisory"],"source":"secalert@redhat.com"},{"url":"https://lists.gnu.org/archive/html/qemu-devel/2016-04/msg01118.html","tags":["Patch","Third Party Advisory"],"source":"secalert@redhat.com"},{"url":"https://security.gentoo.org/glsa/201609-01","tags":["Third Party Advisory"],"source":"secalert@redhat.com"},{"url":"http://git.qemu.org/?p=qemu.git%3Ba=commit%3Bh=691a02e2ce0c413236a78dee6f2651c937b09fb0","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"http://www.securityfocus.com/bid/86067","tags":["Third Party Advisory","VDB Entry"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"http://www.ubuntu.com/usn/USN-2974-1","tags":["Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://access.redhat.com/errata/RHSA-2017:1856","tags":["Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://access.redhat.com/errata/RHSA-2017:2392","tags":["Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://access.redhat.com/errata/RHSA-2017:2408","tags":["Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=1313686","tags":["Issue Tracking","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.debian.org/debian-lts-announce/2018/11/msg00038.html","tags":["Mailing List","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.gnu.org/archive/html/qemu-devel/2016-04/msg01106.html","tags":["Patch","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.gnu.org/archive/html/qemu-devel/2016-04/msg01118.html","tags":["Patch","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://security.gentoo.org/glsa/201609-01","tags":["Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2016-4020","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}