Medium
Security advisory
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).
- Products
- Not specified
- Affected versions
- Not specified
- Fixed versions
- Not specified
- CVEs
- CVE-2016-4020
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 1 Nov 2026, 07:13 UTC · Revision 1
Source evidence
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).
osv:CVE-2016-4020
Complete source record
{
"id": "da2da0a1d7383472b7182c5f1c5adf035b04fd3bff00ce8a9303506ee453763b",
"url": "https://osv.dev/vulnerability/CVE-2016-4020",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "CVE-2016-4020",
"summary": "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).",
"evidence": "osv:CVE-2016-4020",
"products": [],
"severity": "medium",
"structured": {
"id": "CVE-2016-4020",
"aliases": [
"CVE-2016-4020"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N"
}
],
"affected": [
{
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{
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"type": "GIT",
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},
{
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}
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"v2.1.0-rc2",
"v2.1.0-rc3",
"v2.0.0",
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"v2.0.0-rc3",
"v2.0.0-rc2",
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"v1.4.0-rc1",
"v1.4.0-rc0",
"v1.3.0",
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"v1.3.0-rc1",
"v1.3.0-rc0",
"v1.2.0",
"v1.2.0-rc3",
"v1.2.0-rc2",
"v1.2.0-rc1",
"v1.2.0-rc0",
"v1.1.0",
"v1.1.0-rc4",
"v1.1.0-rc3",
"v1.1.0-rc2",
"v1.1-rc2",
"v1.1-rc1",
"v1.1-rc0",
"v1.0",
"v1.0-rc4",
"v1.0-rc3",
"v1.0-rc2",
"v1.0-rc1",
"v1.0-rc0",
"v0.14.0-rc0",
"v0.13.0-rc0",
"v0.12.0-rc0",
"v0.11.0-rc0",
"v0.5.0",
"v0.4.4",
"v0.4.3",
"v0.4.2",
"v0.4.1",
"v0.4.0",
"v0.3.0",
"v0.2.0",
"v0.1.6",
"v0.1.5",
"v0.1.4",
"v0.1.3",
"v0.1.1",
"v0.1.0"
],
"database_specific": {
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}
},
{
"ranges": [
{
"repo": "https://gitlab.com/qemu-project/qemu",
"type": "GIT",
"events": [
{
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},
{
"last_affected": "529d45e151d82a772cd9b9af64bb25f88fba6567"
}
],
"database_specific": {
"extracted_events": [
{
"cpe": "cpe:2.3:a:qemu:qemu:*:*:*:*:*:*:*:*",
"range": [
{
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},
{
"last_affected": "2.6.2"
}
],
"source": "CPE_RANGE"
}
]
}
}
],
"versions": [
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"v2.6.1",
"v2.6.0",
"v2.6.0-rc5",
"v2.6.0-rc4",
"v2.6.0-rc3",
"v2.6.0-rc2",
"v2.6.0-rc1",
"v2.6.0-rc0",
"v2.5.0",
"v2.5.0-rc4",
"v2.5.0-rc3",
"v2.5.0-rc2",
"v2.5.0-rc1",
"v2.5.0-rc0",
"v2.4.0",
"v2.4.0-rc4",
"v2.4.0-rc3",
"v2.3.0",
"v2.4.0-rc2",
"v2.4.0-rc1",
"v2.4.0-rc0",
"v2.3.0-rc4",
"v2.3.0-rc3",
"v2.3.0-rc2",
"v2.3.0-rc1",
"v2.3.0-rc0",
"v2.2.0",
"v2.2.0-rc3",
"v2.2.0-rc5",
"v2.2.0-rc4",
"v2.2.0-rc2",
"v2.2.0-rc1",
"v2.2.0-rc0",
"v2.1.0",
"v2.1.0-rc5",
"v2.1.0-rc4",
"v2.1.0-rc2",
"v2.1.0-rc3",
"v2.0.0",
"v2.1.0-rc1",
"v2.1.0-rc0",
"v2.0.0-rc3",
"v2.0.0-rc2",
"v2.0.0-rc1",
"v2.0.0-rc0",
"v1.7.0",
"v1.7.0-rc2",
"v1.7.0-rc1",
"v1.7.0-rc0",
"v1.6.0",
"v1.6.0-rc3",
"v1.6.0-rc2",
"v1.6.0-rc1",
"v1.6.0-rc0",
"v1.5.0",
"v1.5.0-rc3",
"v1.5.0-rc2",
"v1.5.0-rc1",
"v1.5.0-rc0",
"v1.4.0",
"v1.4.0-rc2",
"v1.4.0-rc1",
"v1.4.0-rc0",
"v1.3.0",
"v1.3.0-rc2",
"v1.3.0-rc1",
"v1.3.0-rc0",
"v1.2.0",
"v1.2.0-rc3",
"v1.2.0-rc2",
"v1.2.0-rc1",
"v1.2.0-rc0",
"v1.1.0",
"v1.1.0-rc4",
"v1.1.0-rc3",
"v1.1.0-rc2",
"v1.1-rc2",
"v1.1-rc1",
"v1.1-rc0",
"v1.0",
"v1.0-rc4",
"v1.0-rc3",
"v1.0-rc2",
"v1.0-rc1",
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"v0.13.0-rc0",
"v0.12.0-rc0",
"v0.11.0-rc0",
"v0.5.0",
"v0.4.4",
"v0.4.3",
"v0.4.2",
"v0.4.1",
"v0.4.0",
"v0.3.0",
"v0.2.0",
"v0.1.6",
"v0.1.5",
"v0.1.4",
"v0.1.3",
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"v0.1.0"
],
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2016-4020.json"
}
}
],
"modified": "2026-10-24T10:30:50.300132890Z",
"provider": "osv",
"references": [
"https://access.redhat.com/errata/RHSA-2017:1856",
"https://access.redhat.com/errata/RHSA-2017:2392",
"https://access.redhat.com/errata/RHSA-2017:2408",
"https://lists.debian.org/debian-lts-announce/2018/11/msg00038.html",
"https://security.gentoo.org/glsa/201609-01",
"https://bugzilla.redhat.com/show_bug.cgi?id=1313686",
"https://lists.gnu.org/archive/html/qemu-devel/2016-04/msg01106.html",
"https://lists.gnu.org/archive/html/qemu-devel/2016-04/msg01118.html"
],
"provider_metadata": {
"unresolved_ranges": [
{
"cpes": [
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"cpe:2.3:o:canonical:ubuntu_linux:14.04:*:*:*:esm:*:*:*",
"cpe:2.3:o:canonical:ubuntu_linux:15.10:*:*:*:*:*:*:*",
"cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:lts:*:*:*"
],
"vendor_product": "canonical:ubuntu_linux",
"extracted_events": [
{
"range": [
{
"introduced": "12.04"
},
{
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},
{
"introduced": "14.04"
},
{
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},
{
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{
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},
{
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},
{
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}
],
"source": "CPE_STRING"
}
]
},
{
"cpes": [
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],
"vendor_product": "debian:debian_linux",
"extracted_events": [
{
"range": [
{
"introduced": "8.0"
},
{
"last_affected": "8.0"
}
],
"source": "CPE_STRING"
}
]
},
{
"cpes": [
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],
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{
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{
"introduced": "7.0"
},
{
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}
],
"source": "CPE_STRING"
}
]
},
{
"cpes": [
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"cpe:2.3:o:redhat:enterprise_linux_eus:7.6:*:*:*:*:*:*:*",
"cpe:2.3:o:redhat:enterprise_linux_eus:7.7:*:*:*:*:*:*:*"
],
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{
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{
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{
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{
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},
{
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},
{
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{
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},
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],
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]
},
{
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},
{
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"cpe:2.3:o:redhat:enterprise_linux_server_aus:7.6:*:*:*:*:*:*:*",
"cpe:2.3:o:redhat:enterprise_linux_server_aus:7.7:*:*:*:*:*:*:*"
],
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{
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{
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],
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{
"range": [
{
"introduced": "7.6"
},
{
"last_affected": "7.6"
},
{
"introduced": "7.7"
},
{
"last_affected": "7.7"
}
],
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}
]
},
{
"cpes": [
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],
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{
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{
"introduced": "7.0"
},
{
"last_affected": "7.0"
}
],
"source": "CPE_STRING"
}
]
},
{
"cpes": [
"cpe:2.3:a:redhat:openstack:10:*:*:*:*:*:*:*",
"cpe:2.3:a:redhat:openstack:11:*:*:*:*:*:*:*",
"cpe:2.3:a:redhat:openstack:6.0:*:*:*:*:*:*:*",
"cpe:2.3:a:redhat:openstack:7.0:*:*:*:*:*:*:*",
"cpe:2.3:a:redhat:openstack:8:*:*:*:*:*:*:*",
"cpe:2.3:a:redhat:openstack:9:*:*:*:*:*:*:*"
],
"vendor_product": "redhat:openstack",
"extracted_events": [
{
"range": [
{
"introduced": "6.0"
},
{
"last_affected": "6.0"
},
{
"introduced": "7.0"
},
{
"last_affected": "7.0"
},
{
"introduced": "8"
},
{
"last_affected": "8"
},
{
"introduced": "9"
},
{
"last_affected": "9"
},
{
"introduced": "10"
},
{
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},
{
"introduced": "11"
},
{
"last_affected": "11"
}
],
"source": "CPE_STRING"
}
]
},
{
"cpes": [
"cpe:2.3:a:redhat:virtualization:4.0:*:*:*:*:*:*:*"
],
"vendor_product": "redhat:virtualization",
"extracted_events": [
{
"range": [
{
"introduced": "4.0"
},
{
"last_affected": "4.0"
}
],
"source": "CPE_STRING"
}
]
}
]
}
},
"related_cves": [
{
"value": "CVE-2016-4020",
"evidence": "/id"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 437208,
"published_at": "2016-05-25T15:59:04.927+00:00"
}