CVE-2021-3929Public exploit

Guest-triggered host process crash via reentrant NVMe DMA

Published Aug 25, 2022 · Updated Feb 28, 2025

Use-after-free in QEMU NVMe emulation before 7.0.0-rc0 allows guest OS users to crash the host process through a crafted DMA request. The nvme_tx path performs DMA to the controller's own MMIO without an overlap check, allowing a reentrant write to reset the controller and free live queue structures. Guest control of an emulated NVMe request is required; the upstream reproducer demonstrates a QEMU process crash, not host-process code execution.

CVSS severity8.2
High
EPSS probability0.67%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in QEMU NVMe emulation before 7.0.0-rc0 allows guest OS users to crash the host process through a crafted DMA request. The nvme_tx path performs DMA to the controller's own MMIO without an overlap check, allowing a reentrant write to reset the controller and free live queue structures. Guest control of an emulated NVMe request is required; the upstream reproducer demonstrates a QEMU process crash, not host-process code execution.

The record

CVE
CVE-2021-3929
Published
Aug 25, 2022
Updated
Feb 28, 2025
Vendor
QEMU Project
Product
QEMU
Classifications
CWE-416, T1611
Attack vector
local
Privileges
admin

Timeline

How it unfolded

  1. Aug 25, 2022CVE publishedPublication date reported by the CVE source.
  2. Feb 28, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=Fixed in qemu-kvm 7.0.0-rc0

What conditions does exploitation require?

Attack vectorlocal
Required privilegesadmin

What is affected?

QEMU Project · QEMUversion=Fixed in qemu-kvm 7.0.0-rc0

Published CVSS scores

8.2NIST NVDCVSS:3.1/AV:L/AC:L/PR:H/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.

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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
Privilegesadmin
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-416Use After Free
T1611Escape to Host

Public exploit references

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

Technologies

Your stack

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Your stack

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