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Fencer Intel
medium 6.5

CVE-2021-4147 json

A flaw was found in the libvirt libxl driver.

published 4y ago modified 4mo ago also EUVD-2021-34015

cvss
6.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 15%
public exploits
0
none known

Summary

A flaw was found in the libvirt libxl driver. A malicious guest could continuously reboot itself and cause libvirtd on the host to deadlock or crash, resulting in a denial of service condition.

Patch / fix

  • redhat libvirt 2.33.0
  • libvirt Debian 14, Debian 13, Debian 12 7.10.0-2

debian advisories DEBIAN-CVE-2021-4147

  • libvirt Ubuntu 18.04 LTS 4.0.0-1ubuntu8.21
  • libvirt Ubuntu 20.04 LTS 6.0.0-0ubuntu8.16
  • libvirt Ubuntu Pro 16.04 LTS 1.3.1-1ubuntu10.31+esm1

ubuntu advisories UBUNTU-CVE-2021-4147

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

  • libvirt SLES 15 SP2-BCL, SLE Real Time 15 SP2, SLE Micro 5.0 +8 more 6.0.0-13.24.1
  • libvirt SLES for SAP 15 SP1, SLES 15 SP1-LTSS, SLES 15 SP1-BCL +3 more 5.1.0-17.1
  • libvirt SLES for SAP 12 SP4, SLES 12 SP4-LTSS, OpenStack Cloud Crowbar 9 +1 more 4.0.0-8.26.1
  • libvirt SLES for SAP 12 SP3, SLES 12 SP3-LTSS, SLES 12 SP3-BCL +3 more 3.3.0-5.49.1
  • libvirt SLES for SAP 12 SP5, SLES 12 SP5, SLE Software Development Kit 12 SP5 5.1.0-13.28.2
  • libvirt SLES for SAP 15, SLES 15-LTSS, SLE High Performance Computing 15-LTSS +1 more 4.0.0-9.40.1
  • libvirt SLE Module for Server Applications 15 SP3, SLE Module for Basesystem 15 SP3, SLE Micro 5.1 7.1.0-6.11.1

suse advisories SUSE-SU-2022:0045-2SUSE-SU-2022:0128-1SUSE-SU-2022:0045-1SUSE-SU-2022:0042-1SUSE-SU-2022:0041-1SUSE-SU-2022:0032-1

  • libvirt openSUSE Tumbleweed 8.0.0-1.1
  • libvirt openSUSE Leap 15.3 7.1.0-6.11.1

opensuse advisories openSUSE-SU-2024:11758-1openSUSE-SU-2022:0021-1

Is CVE-2021-4147 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

Check with Fencer

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-2021-4147 updated cvss 6.5

libvirt: deadlock and crash in libxl driver

  • Red Hat Enterprise Linux 6 libvirt, libvirt-client, libvirt-python, libvirt-lock-sanlock Red Hat Enterprise Linux 7 libvirt, libvirt-nss, libvirt-libs, libvirt-admin, libvirt-client, libvirt-daemon, +24 more Red Hat Enterprise Linux 8 libvirt, libvirt-nss, libvirt-libs, libvirt-admin, libvirt-client, libvirt-daemon, +22 more Red Hat Enterprise Linux 8 Advanced Virtualization libvirt, libvirt-nss, libvirt-libs, libvirt-admin, libvirt-client, libvirt-daemon, +22 more Red Hat Enterprise Linux 9 libvirt, libvirt-nss, libvirt-libs, libvirt-client, libvirt-daemon, libvirt-ssh-proxy, +25 more
    not affected: vulnerable code not present

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

0.24% chance of exploitation in the next 30 days, higher than 15% of all scored CVEs (FIRST EPSS, 2026-11-09).

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 4.9 AV:L/AC:L/Au:N/C:N/I:N/A:C

Affected products

  • n/a libvirt

Classification

Weakness

References

Sources

Fencer Intel 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.