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Fencer Vulns
medium 6.5

CVE-2016-9921 json

Quick emulator (Qemu) built with the Cirrus CLGD 54xx VGA Emulator support is vulnerable to a divide by zero issue.

published 2016-12-23 9 y ago modified 2026-06-17 4 mo ago also EUVD-2016-10708

cvss
6.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 35%
public exploits
0
none known

Summary

Quick emulator (Qemu) built with the Cirrus CLGD 54xx VGA Emulator support is vulnerable to a divide by zero issue. It could occur while copying VGA data when cirrus graphics mode was set to be VGA. A privileged user inside guest could use this flaw to crash the Qemu process instance on the host, resulting in DoS.

Patch / fix

  • qemu Debian 14, Debian 13, Debian 12 1:2.8+dfsg-1

debian advisories DEBIAN-CVE-2016-9921

  • qemu Ubuntu 14.04 LTS 2.0.0+dfsg-2ubuntu1.33
  • qemu Ubuntu 16.04 LTS 1:2.5+dfsg-5ubuntu10.11

ubuntu advisories UBUNTU-CVE-2016-9921

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • qemu-kvm-rhev openstack 11, openstack 10, openstack 9 +3 more 10:2.9.0-10.el7
  • qemu-img-rhev openstack 11, openstack 10, openstack 9 +3 more 10:2.9.0-10.el7
  • qemu-kvm-tools-rhev openstack 11, openstack 10, openstack 9 +3 more 10:2.9.0-10.el7
  • qemu-kvm-common-rhev openstack 11, openstack 10, openstack 9 +3 more 10:2.9.0-10.el7
  • qemu-kvm-rhev RHEL 7 10:2.9.0-14.el7
  • qemu-img-rhev RHEL 7 10:2.9.0-14.el7
  • qemu-kvm-tools-rhev RHEL 7 10:2.9.0-14.el7
  • qemu-kvm-common-rhev RHEL 7 10:2.9.0-14.el7

red hat advisories RHSA-2017:2408RHSA-2017:2392

  • kvm SLES 11 SP3-TERADATA, SLES 11 SP3-LTSS, SLE Point of Sale 11 SP3 1.4.2-53.11.1
  • qemu SLES for SAP 12 SP1, SLES 12 SP1, SLED 12 SP1 2.3.1-32.11
  • kvm SLES for SAP 11 SP4, SLES 11 SP4 1.4.2-59.1
  • xen SLES 11 SP3-LTSS, SLE Point of Sale 11 SP3, OpenStack Cloud 5 +2 more 4.2.5_21-35.1
  • xen SLES for SAP 11 SP4, SLES 11 SP4, SLE Software Development Kit 11 SP4 4.4.4_14-51.1
  • qemu SLES for SAP 12 SP2, SLES for Raspberry Pi 12 SP2, SLES 12 SP2 +1 more 2.6.2-41.9.1
  • xen SLES for SAP 12 SP1, SLES 12 SP1, SLED 12 SP1 +1 more 4.5.5_06-22.11.2
  • xen SLES for SAP 12 SP2, SLES 12 SP2, SLED 12 SP2 +1 more 4.7.1_06-31.1

suse advisories SUSE-SU-2017:3084-1SUSE-SU-2017:1241-1SUSE-SU-2017:1135-1SUSE-SU-2017:0718-1SUSE-SU-2017:0661-1SUSE-SU-2017:0647-1

  • qemu openSUSE Tumbleweed 6.1.0-32.1
  • xen openSUSE Tumbleweed 4.15.1_01-1.2

opensuse advisories openSUSE-SU-2024:11287-1openSUSE-SU-2024:11520-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2016-9921 updated cvss 3.0

Qemu: display: cirrus_vga: a divide by zero in cirrus_do_copy

  • Red Hat Enterprise Linux 5 kvm, xen Red Hat Enterprise Linux 6 qemu-img, qemu-kvm, qemu-kvm-rhev, qemu-kvm-tools, qemu-guest-agent, qemu-guest-agent-win32 Red Hat Enterprise Linux 7 qemu-img, qemu-kvm, libcacard, qemu-kvm-tools, libcacard-tools, qemu-kvm-common, +1 more Red Hat Enterprise Linux OpenStack Platform 5 (Icehouse) qemu-kvm-rhev
    affected: no fix planned “Will not fix”
  • Red Hat Enterprise Linux OpenStack Platform 6.0 (Juno) for RHEL 7 qemu-img-rhev 2.9.0-10.el7, qemu-kvm-rhev 2.9.0-10.el7, qemu-kvm-tools-rhev 2.9.0-10.el7, qemu-kvm-common-rhev 2.9.0-10.el7 Red Hat Enterprise Linux OpenStack Platform 7.0 (Kilo) for RHEL 7 qemu-img-rhev 2.9.0-10.el7, qemu-kvm-rhev 2.9.0-10.el7, qemu-kvm-tools-rhev 2.9.0-10.el7, qemu-kvm-common-rhev 2.9.0-10.el7 Red Hat OpenStack Platform 8.0 (Liberty) qemu-img-rhev 2.9.0-10.el7, qemu-kvm-rhev 2.9.0-10.el7, qemu-kvm-tools-rhev 2.9.0-10.el7, qemu-kvm-common-rhev 2.9.0-10.el7 Red Hat OpenStack Platform 9.0 qemu-img-rhev 2.9.0-10.el7, qemu-kvm-rhev 2.9.0-10.el7, qemu-kvm-tools-rhev 2.9.0-10.el7, qemu-kvm-common-rhev 2.9.0-10.el7 Red Hat OpenStack Platform 10.0 qemu-img-rhev 2.9.0-10.el7, qemu-kvm-rhev 2.9.0-10.el7, qemu-kvm-tools-rhev 2.9.0-10.el7, qemu-kvm-common-rhev 2.9.0-10.el7 Red Hat OpenStack Platform 11.0 qemu-img-rhev 2.9.0-10.el7, qemu-kvm-rhev 2.9.0-10.el7, qemu-kvm-tools-rhev 2.9.0-10.el7, qemu-kvm-common-rhev 2.9.0-10.el7
    fixed: vendor fix RHSA-2017:2408
  • Red Hat Virtualization 4 Management Agent for RHEL 7 Hosts qemu-img-rhev 2.9.0-14.el7, qemu-kvm-rhev 2.9.0-14.el7, qemu-kvm-tools-rhev 2.9.0-14.el7, qemu-kvm-common-rhev 2.9.0-14.el7
    fixed: vendor fix RHSA-2017:2392

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

0.41% chance of exploitation in the next 30 days, higher than 35% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 6.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H
NVD 2.0 2.1 AV:L/AC:L/Au:N/C:N/I:N/A:P

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.