CVE-2021-4147: A flaw was found in the libvirt libxl driver

Q: How do I fix CVE-2021-4147?

libvirt: upgrade to 2.33.0; fedora: mitigate or apply the listed mitigation; ontap select deploy administration utility: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Q: Is CVE-2021-4147 being exploited?

CVE-2021-4147 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2021-4147 affect?

CVE-2021-4147 affects libvirt, fedora, ontap select deploy administration utility. Severity is medium (CVSS 6.5). 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.

Q: How urgent is CVE-2021-4147?

Priority 32/100. On your watchlist

Routine

MEDIUM 6.5WATCHLISTUPGRADEMITIGATEMITIGATE

CVE-2021-4147 is a medium-severity flaw (CVSS 6.5) affecting libvirt, fedora, ontap select deploy administration utility. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	6.5 (Medium)
Attack vector	Local
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.2% (top 84%)
CISA exploited list	No
Weakness	CWE-667
Published	2022-03-25
Last modified	2026-06-17

Publisher (CNA): Red Hat, Inc. · Vendor: fedoraproject · netapp · redhat

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2022-03-25 19:15 UTCPublished CVE record published
2026-06-17 04:19 UTCUpdated Record last modified

redhat libvirt UPGRADE

Affected: < 2.33.0

Fixed in: 2.33.0

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy libvirt || rpm -q libvirt || libvirt --version

2. UPGRADE to 2.33.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade libvirt

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade libvirt

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

fedoraproject fedora MITIGATE

Affected: 35

Fixed in: no fixed release known

Safe to downgrade to: a release before 35

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

netapp ontap select deploy administration utility MITIGATE

Affected: all versions

Fixed in: no fixed release known

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy ontap-select-deploy-administration-utility || rpm -q ontap-select-deploy-administration-utility || ontap-select-deploy-administration-utility --version

No fixed or unaffected release known

Apply the vendor mitigation from the advisory, disable the affected feature, or restrict network access.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2021-4147?

libvirt: upgrade to 2.33.0; fedora: mitigate or apply the listed mitigation; ontap select deploy administration utility: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2021-4147 being exploited?

CVE-2021-4147 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2021-4147 affect?

CVE-2021-4147 affects libvirt, fedora, ontap select deploy administration utility. Severity is medium (CVSS 6.5). 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.

How urgent is CVE-2021-4147?

Priority 32/100. On your watchlist

Related CVEs

CVE-2024-8235 MEDIUM 6.2 UPGRADE A flaw was found in libvirt
CVE-2024-2496 MEDIUM 5.0 UPGRADE MITIGATE A NULL pointer dereference flaw was found in the udevConnectListAllInterfaces() function in libvirt
CVE-2023-3750 MEDIUM 6.5 MITIGATE MITIGATE A flaw was found in libvirt
CVE-2023-2700 MEDIUM 5.5 DOWNGRADE MITIGATE A vulnerability was found in libvirt
CVE-2022-0897 MEDIUM 4.3 UPGRADE MITIGATE A flaw was found in the libvirt nwfilter driver

References

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