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Fencer Vulns
high 8.2

CVE-2021-3750 json

A DMA reentrancy issue was found in the USB EHCI controller emulation of QEMU.

published 2022-05-02 4 y ago modified 2026-06-17 4 mo ago also EUVD-2021-27025

cvss
8.2
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 44%
public exploits
0
none known

Summary

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.

Patch / fix

  • qemu qemu 7.0.0
  • qemu Debian 14, Debian 13, Debian 12 1:7.0+dfsg-1

debian advisories DEBIAN-CVE-2021-3750

  • qemu Ubuntu 18.04 LTS 1:2.11+dfsg-1ubuntu7.41
  • qemu Ubuntu 20.04 LTS 1:4.2-3ubuntu6.24
  • qemu Ubuntu 22.04 LTS 1:6.2+dfsg-2ubuntu6.6

ubuntu advisories UBUNTU-CVE-2021-3750

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • qemu-kvm RHEL 9 17:7.0.0-13.el9
  • qemu-img RHEL 9 17:7.0.0-13.el9
  • qemu-kvm-core RHEL 9 17:7.0.0-13.el9
  • qemu-kvm-tools RHEL 9 17:7.0.0-13.el9
  • qemu-pr-helper RHEL 9 17:7.0.0-13.el9
  • qemu-kvm-common RHEL 9 17:7.0.0-13.el9
  • qemu-guest-agent RHEL 9 17:7.0.0-13.el9
  • qemu-kvm-audio-pa RHEL 9 17:7.0.0-13.el9

red hat advisories RHSA-2024:0404RHSA-2022:7967RHSA-2024:0569RHSA-2023:6980

  • qemu SLES for SAP 12 SP5, SLES 12 SP5 3.1.1.1-72.1
  • qemu SLE Module for Server Applications 15 SP4, SLE Module for Basesystem 15 SP4, SLE Micro 5.4 +2 more 6.2.0-150400.37.23.1
  • qemu SLES for SAP 15 SP2, SLES 15 SP2-LTSS, SLE High Performance Computing 15 SP2-LTSS +1 more 4.2.1-150200.79.1
  • qemu SLES for SAP 15 SP3, SLES 15 SP3-LTSS, SLE Micro 5.2 +6 more 5.2.0-150300.127.3
  • qemu SLES for SAP 15 SP1, SLES 15 SP1-LTSS, SLE High Performance Computing 15 SP1-LTSS 3.1.1.1-150100.80.51.5

suse advisories SUSE-SU-2024:1395-1SUSE-SU-2023:4056-1SUSE-SU-2023:3800-1SUSE-SU-2023:3721-1SUSE-SU-2023:3444-1

  • SLOF AlmaLinux 8 20210217-1.module_el8.6.0+2880+7d9e3703
  • hivex AlmaLinux 8 1.3.18-23.module_el8.6.0+2880+7d9e3703
  • hivex AlmaLinux 8 1.3.18-23.module_el8.6.0+3161+a07c0ea5
  • netcf AlmaLinux 8 0.2.8-12.module_el8.6.0+2880+7d9e3703
  • netcf AlmaLinux 8 0.2.8-12.module_el8.6.0+3161+a07c0ea5
  • swtpm AlmaLinux 8 0.7.0-4.20211109gitb79fd91.module_el8.7.0+3346+68867adb
  • libnbd AlmaLinux 8 1.6.0-5.module_el8.6.0+2880+7d9e3703
  • libnbd AlmaLinux 8 1.6.0-5.module_el8.6.0+3161+a07c0ea5

almalinux advisories ALSA-2023:6980ALSA-2023:6368ALSA-2022:7967

  • hivex Rocky Linux 8 1.3.18-23.module+el8.10.0+1590+a67ab969
  • hivex Rocky Linux 8 1.3.18-23.module+el8.10.0+1835+43f01cbb
  • netcf Rocky Linux 8 0.2.8-12.module+el8.10.0+1835+43f01cbb
  • netcf Rocky Linux 8 0.2.8-12.module+el8.10.0+1590+a67ab969
  • swtpm Rocky Linux 8 0.7.0-4.20211109gitb79fd91.module+el8.10.0+1590+a67ab969
  • swtpm Rocky Linux 8 0.7.0-4.20211109gitb79fd91.module+el8.10.0+1835+43f01cbb
  • libnbd Rocky Linux 8 1.6.0-5.module+el8.10.0+1835+43f01cbb
  • libnbd Rocky Linux 8 1.6.0-5.module+el8.10.0+1590+a67ab969

rocky linux advisories RLSA-2023:6980RLSA-2022:7967

  • qemu Azure Linux 3.0 6.2.0-18
  • qemu CBL-Mariner 2.0 6.2.0-16

azure linux advisories AZL-35151AZL-9701

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2021-3750 updated cvss 7.5

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

  • Red Hat Enterprise Linux 6 qemu-img, qemu-kvm, qemu-kvm-tools, qemu-guest-agent, qemu-guest-agent-win32 Red Hat Enterprise Linux 7 qemu-img, qemu-kvm, libcacard, qemu-img-ma, qemu-kvm-ma, qemu-kvm-tools, +5 more
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 8 Advanced Virtualization qemu-img, qemu-kvm, qemu-kiwi, qemu-kvm-core, qemu-kvm-tests, qemu-kvm-common, +9 more
    affected: workaround, no fix available, no fix planned “Will not fix”
  • Red Hat OpenStack Platform 10 (Newton) qemu-img-rhev, qemu-kvm-rhev, qemu-kvm-tools-rhev, qemu-kvm-common-rhev Red Hat OpenStack Platform 13 (Queens) qemu-img-rhev, qemu-kvm-rhev, qemu-kvm-tools-rhev, qemu-kvm-common-rhev
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat CodeReady Linux Builder (v. 8) libnbd 1.6.0-5.module+el8.9.0+18724+20190c23, netcf 0.2.8-12.module+el8.9.0+18724+20190c23, hivex 1.3.18-23.module+el8.9.0+18724+20190c23, nbdfuse 1.6.0-5.module+el8.9.0+18724+20190c23, SLOF 20210217-1.module+el8.9.0+18724+20190c23, libvirt 8.0.0-22.module+el8.9.0+19544+b3045133, +38 more
    fixed: vendor fix RHSA-2023:6980
  • Red Hat CodeReady Linux Builder EUS (v.8.6) libnbd 1.6.0-5.module+el8.6.0+14480+c0a3aa0f, netcf 0.2.8-12.module+el8.6.0+14480+c0a3aa0f, hivex 1.3.18-23.module+el8.6.0+14480+c0a3aa0f, nbdfuse 1.6.0-5.module+el8.6.0+14480+c0a3aa0f, SLOF 20210217-1.module+el8.6.0+14480+c0a3aa0f, libiscsi 1.18.0-8.module+el8.6.0+14480+c0a3aa0f, +38 more
    fixed: vendor fix RHSA-2024:0404
  • Red Hat CodeReady Linux Builder EUS (v.8.8) libnbd 1.6.0-5.module+el8.8.0+16781+9f4724c2, netcf 0.2.8-12.module+el8.8.0+16781+9f4724c2, hivex 1.3.18-23.module+el8.8.0+16781+9f4724c2, nbdfuse 1.6.0-5.module+el8.8.0+16781+9f4724c2, SLOF 20210217-2.module+el8.8.0+20737+daad9f3b, seabios 1.16.0-4.module+el8.8.0+19627+2d14cb21, +38 more
    fixed: vendor fix RHSA-2024:0569
  • Red Hat Enterprise Linux AppStream (v. 8) libnbd 1.6.0-5.module+el8.9.0+18724+20190c23, netcf 0.2.8-12.module+el8.9.0+18724+20190c23, hivex 1.3.18-23.module+el8.9.0+18724+20190c23, nbdfuse 1.6.0-5.module+el8.9.0+18724+20190c23, nbdkit 1.24.0-5.module+el8.9.0+18724+20190c23, SLOF 20210217-1.module+el8.9.0+18724+20190c23, +104 more
    fixed: vendor fix RHSA-2023:6980
  • Red Hat Enterprise Linux AppStream (v. 9) qemu-img 7.0.0-13.el9, qemu-kvm 7.0.0-13.el9, qemu-kvm-core 7.0.0-13.el9, qemu-kvm-tools 7.0.0-13.el9, qemu-pr-helper 7.0.0-13.el9, qemu-kvm-common 7.0.0-13.el9, +15 more
    fixed: vendor fix RHSA-2022:7967
show 2 more
  • Red Hat Enterprise Linux AppStream EUS (v.8.6) libnbd 1.6.0-5.module+el8.6.0+14480+c0a3aa0f, netcf 0.2.8-12.module+el8.6.0+14480+c0a3aa0f, hivex 1.3.18-23.module+el8.6.0+14480+c0a3aa0f, nbdfuse 1.6.0-5.module+el8.6.0+14480+c0a3aa0f, nbdkit 1.24.0-4.module+el8.6.0+14480+c0a3aa0f, SLOF 20210217-1.module+el8.6.0+14480+c0a3aa0f, +104 more
    fixed: vendor fix RHSA-2024:0404
  • Red Hat Enterprise Linux AppStream EUS (v.8.8) libnbd 1.6.0-5.module+el8.8.0+16781+9f4724c2, netcf 0.2.8-12.module+el8.8.0+16781+9f4724c2, hivex 1.3.18-23.module+el8.8.0+16781+9f4724c2, nbdfuse 1.6.0-5.module+el8.8.0+16781+9f4724c2, nbdkit 1.24.0-5.module+el8.8.0+17308+05924798, SLOF 20210217-2.module+el8.8.0+20737+daad9f3b, +104 more
    fixed: vendor fix RHSA-2024:0569

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

0.51% chance of exploitation in the next 30 days, higher than 44% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • gitlab.com https://gitlab.com/qemu-project/qemu/-/issues/541 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 8.2 CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
NVD 2.0 4.6 AV:L/AC:L/Au:N/C:P/I:P/A:P

Affected products

  • n/a QEMU

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.