CVE-2016-4020: canonical ubuntu_linux
Vulnerability summary
CVE-2016-4020 is a medium (CVSS 6.5) vulnerability in canonical ubuntu_linux. EPSS estimates a 0.37% chance of exploitation in the next 30 days, higher than 31.2% of scored vulnerabilities.
Not severe (CVSS 6.5, local access); no exploitation reported by the 5 checked sources
Source freshness unavailable
How is this decided?Advisory lineage
Upstream 0 · Downstream 17 · Related 10Timeline
- 25-05-2016PublishedVulnerability first disclosed.
- 06-08-2024Last modifiedVulnerability information updated.
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).
CVSS metrics
5 scores · 3 sources · 3 versions- OSV · UbuntuEcosystem advisory · calculated6.5MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N
- OSV · DebianEcosystem advisory · calculated6.5MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N
EPSS trend
Probability
0.37%
Chance of exploitation in the next 30 days
Percentile
31%
Versus all other CVEs
30-day change
No change 0.00 pp
From 0.37% on 04-10-2026
Known exploited
Compare KEV catalogs
CISA KEVNot in the CISA KEV catalog.
ENISA CNWNot in the ENISA CNW catalog.
CIRCLNot in the CIRCL catalog.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeNo weakness data has been published for this record.
Affected systems
Known conditions: local access, low-privilege account, no user interaction (CVSS vector). Other conditions: not stated in public data.
Redhat8 products
- enterprise_linux_desktop7.0
- enterprise_linux_eus7.4 | 7.5 | 7.6 | 7.7
- enterprise_linux_server7.0
- enterprise_linux_server_aus7.4 | 7.6 | 7.7
- enterprise_linux_server_tus7.6 | 7.7
Debian2 products
- qemu< 1:2.6+dfsg-2
- debian_linuxEOL8.0
Canonical1 product
- ubuntu_linuxEOL12.04 | 14.04 | 15.10 | 16.04
Qemu1 product
- qemu≤ 2.6.2
Ubuntu1 product
- qemu< 2.0.0+dfsg-2ubuntu1.24 | < 1:2.5+dfsg-5ubuntu10.1
5 vendors · 13 products
References
16 links- lists.gnu.org/archive/html/qemu-devel/2016-04/msg01106.htmlMailing ListX Refsource MLISTPatchThird Party Advisory
- lists.gnu.org/archive/html/qemu-devel/2016-04/msg01118.htmlMailing ListX Refsource MLISTPatchThird Party AdvisoryREPORT
lists.debian.org/debian-lts-announce/2018/11/msg00038.htmlMailing ListX Refsource MLISTThird Party Advisory