CVE-2021-45464Public exploit

Guest-to-host code execution via virtio out-of-bounds write

Published Apr 15, 2023 · Updated Feb 6, 2025

Out-of-bounds write in kvmtool through commit 39181fc allows guest OS users to execute arbitrary code on the Linux host. The published record locates the flaw in virtio/balloon.c and virtio/pci.c but does not disclose which guest-controlled value lacks bounds checking. Exploitation requires control of a guest OS with the virtio balloon device exposed and crosses the virtualization boundary into the host process.

CVSS severity8.8
High
EPSS probability0.38%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Out-of-bounds write in kvmtool through commit 39181fc allows guest OS users to execute arbitrary code on the Linux host. The published record locates the flaw in virtio/balloon.c and virtio/pci.c but does not disclose which guest-controlled value lacks bounds checking. Exploitation requires control of a guest OS with the virtio balloon device exposed and crosses the virtualization boundary into the host process.

The record

CVE
CVE-2021-45464
Published
Apr 15, 2023
Updated
Feb 6, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-787, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 15, 2023CVE publishedPublication date reported by the CVE source.
  2. Feb 6, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

8.8CISA-ADPCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
8.8NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-787Out-of-bounds Write
T1068Exploitation for Privilege Escalation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo