CVE-2021-45464: kvmtool through 39181fc allows an out-of-bounds write, related to virtio/balloon.c and virtio/pci.c

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HIGH 8.8MITIGATE

CVE-2021-45464 is a high-severity flaw (CVSS 8.8) affecting kvmtool. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

kvmtool through 39181fc allows an out-of-bounds write, related to virtio/balloon.c and virtio/pci.c. This allows a guest OS user to execute arbitrary code on the host machine.

Why this priority

High severity
Public exploit reference

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	8.8 (High)
Attack vector	Local
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.4% (top 68%)
CISA exploited list	No
Weakness	CWE-787
Published	2023-04-15
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: kvmtool project

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

Am I affected?

Timeline

2023-04-15 23:15 UTCPublished CVE record published
2026-06-17 04:13 UTCUpdated Record last modified

kvmtool project kvmtool 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 kvmtool || rpm -q kvmtool || kvmtool --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-2021-45464?

kvmtool: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2021-45464 being exploited?

CVE-2021-45464 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-2021-45464 affect?

CVE-2021-45464 affects kvmtool. Severity is high (CVSS 8.8). kvmtool through 39181fc allows an out-of-bounds write, related to virtio/balloon.c and virtio/pci.c. This allows a guest OS user to execute arbitrary code on the host machine.

How urgent is CVE-2021-45464?

Priority 44/100. High severity; Public exploit reference

References

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