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HIGH

CVE-2021-3750

CVSS v3

8.2

HIGH

EPSS Score

0.5 %

exploit probability, as of 2026-10-19

CISA KEV

No

known exploited

Exploitation

—

SSVC status

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Affected and fixed versions

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • hivex-develAlmaLinux:8all versions · fixed in 1.3.18-23.module_el8.6.0+2880+7d9e3703
  • libguestfsAlmaLinux:8all versions · fixed in 1:1.44.0-9.module_el8.7.0+3493+5ed0bd1c.almaand 24 other packages
  • libguestfs-winsupportAlmaLinux:8all versions · fixed in 8.9-1.module_el8.9.0+3662+ef5fc290.alma.1
  • libiscsiAlmaLinux:8all versions · fixed in 1.18.0-8.module_el8.6.0+3161+a07c0ea5and 2 other packages
  • libtpmsAlmaLinux:8all versions · fixed in 0.9.1-2.20211126git1ff6fe1f43.module_el8.9.0+3659+9c8643f3and 1 other package
  • libvirtAlmaLinux:8all versions · fixed in 8.0.0-22.module_el8.9.0+3662+ef5fc290and 27 other packages
  • libvirt-dbusAlmaLinux:8all versions · fixed in 1.3.0-2.module_el8.6.0+3161+a07c0ea5
  • nbdfuseAlmaLinux:8all versions · fixed in 1.6.0-5.module_el8.6.0+2880+7d9e3703and 2 other packages

16 more package ranges on OSV.dev

Vendor advisories

  • CVE-2021-3750 Red Hat Product Security2,928 products fixed · 64 known affected

    QEMU: hcd-ehci: DMA reentrancy issue leads to use-after-free

    qemu-guest-agent as a component of Red Hat Enterprise Linux 6 · qemu-guest-agent-win32 as a component of Red Hat Enterprise Linux 6 · qemu-img as a component of Red Hat Enterprise Linux 6

  • RHSA-2024:0569 Red Hat Product Security938 products fixed

    Red Hat Security Advisory: virt:rhel and virt-devel:rhel security update

  • RHSA-2024:0404 Red Hat Product Security938 products fixed

    Red Hat Security Advisory: virt:rhel and virt-devel:rhel security update

  • RHSA-2023:6980 Red Hat Product Security938 products fixed

    Red Hat Security Advisory: virt:rhel and virt-devel:rhel security, bug fix, and enhancement update

  • RHSA-2022:7967 Red Hat Product Security114 products fixed

    Red Hat Security Advisory: qemu-kvm security, bug fix, and enhancement update

Full record on NVD

Description

A DMA reentrancy issue was found in the USB EHCI controller emulation of QEMU. EHCI does not verify if the Buffer Pointer overlaps with its MMIO region when it transfers the USB packets. Crafted content may be written to the controller's registers and trigger undesirable actions (such as reset) while the device is still transferring packets. This can ultimately lead to a use-after-free issue. A malicious guest could use this flaw to crash the QEMU process on the host, resulting in a denial of service condition, or potentially execute arbitrary code within the context of the QEMU process on the host. This flaw affects QEMU versions before 7.0.0.

Technical details

Published
2022-05-02

Frequently asked questions

What is CVE-2021-3750?

A DMA reentrancy issue was found in the USB EHCI controller emulation of QEMU. EHCI does not verify if the Buffer Pointer overlaps with its MMIO region when it transfers the USB packets. Crafted content may be written to the controller's registers and trigger undesirable actions (such as reset) while the device is still transferring packets. This can ultimately lead to a use-after-free issue. A malicious guest could use this flaw to crash the QEMU process on the host, resulting in a denial of service condition, or potentially execute arbitrary code within the context of the QEMU process on the host. This flaw affects QEMU versions before 7.0.0.

Is CVE-2021-3750 actively exploited?

Active exploitation of CVE-2021-3750 has not been confirmed. Its EPSS score was 0.5% on 2026-10-19, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-3750?

CVE-2021-3750 has a CVSS v3 base score of 8.2 (HIGH severity).

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