CVE-2021-3750Public exploit

Guest-to-host code execution via EHCI DMA reentrancy

Published May 2, 2022 · Updated Aug 3, 2024

Use-after-free in QEMU before 7.0.0 allows guest OS users to crash the host process or execute code via crafted EHCI DMA transfers. EHCI accepts buffer pointers that overlap its MMIO region and writes packet data into controller registers during an active transfer, allowing a reset to free state that remains in use. The guest must control DMA descriptors for an emulated EHCI controller; successful exploitation interrupts the virtual machine service or runs code in the QEMU host process.

CVSS severity8.2
High
EPSS probability0.53%
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 before 7.0.0 allows guest OS users to crash the host process or execute code via crafted EHCI DMA transfers. EHCI accepts buffer pointers that overlap its MMIO region and writes packet data into controller registers during an active transfer, allowing a reset to free state that remains in use. The guest must control DMA descriptors for an emulated EHCI controller; successful exploitation interrupts the virtual machine service or runs code in the QEMU host process.

The record

CVE
CVE-2021-3750
Published
May 2, 2022
Updated
Aug 3, 2024
Vendor
QEMU Project
Product
QEMU
Classifications
CWE-416, T1499.004
Attack vector
local
Privileges
admin

Timeline

How it unfolded

  1. May 2, 2022CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record 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=QEMU before version 7.0.0

What conditions does exploitation require?

Attack vectorlocal
Required privilegesadmin

What is affected?

QEMU Project · QEMUversion=QEMU before version 7.0.0

Published CVSS scores

8.2UbuntuCVSS: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
T1499.004Application or System Exploitation

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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