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Fencer Vulns
high 8.2

CVE-2021-3929 json

A DMA reentrancy issue was found in the NVM Express Controller (NVME) emulation in QEMU.

published 2022-08-25 4 y ago modified 2026-06-17 4 mo ago also EUVD-2021-27145

cvss
8.2
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.7%
EPSS 0.7% chance of exploitation in 30 days, percentile 52%
public exploits
0
none known

Summary

A DMA reentrancy issue was found in the NVM Express Controller (NVME) emulation in QEMU. This CVE is similar to CVE-2021-3750 and, just like it, when the reentrancy write triggers the reset function nvme_ctrl_reset(), data structs will be freed leading 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, executing arbitrary code within the context of the QEMU process on the host.

Patch / fix

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

debian advisories DEBIAN-CVE-2021-3929

  • qemu Ubuntu 22.04 LTS 1:6.2+dfsg-2ubuntu6.2

ubuntu advisories UBUNTU-CVE-2021-3929

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 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 12 SP2-BCL 2.6.2-41.76.1
  • qemu SLES for SAP 15 SP3, SLES 15 SP3-LTSS, SLE Real Time 15 SP3 +7 more 5.2.0-150300.121.2
  • qemu SLES for SAP 12 SP5, SLES 12 SP5 3.1.1.1-66.1
  • 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-2023:3800-1SUSE-SU-2023:3721-1SUSE-SU-2023:2358-1SUSE-SU-2023:0840-1SUSE-SU-2023:0761-1

  • qemu openSUSE Tumbleweed 6.2.0-44.1

opensuse advisories openSUSE-SU-2024:11969-1

  • qemu CBL-Mariner 2.0 6.2.0-13
  • qemu Azure Linux 3.0 6.2.0-18

azure linux advisories AZL-10721AZL-35152

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-2021-3929 updated cvss 8.2

QEMU: nvme: 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 Red Hat Enterprise Linux 8 qemu-img, qemu-kvm, qemu-kvm-core, qemu-kvm-tests, qemu-kvm-common, qemu-guest-agent, +8 more Red Hat Enterprise Linux 8 Advanced Virtualization qemu-img, qemu-kvm, qemu-kiwi, qemu-kvm-core, qemu-kvm-tests, qemu-kvm-common, +9 more Red Hat Enterprise Linux 9 qemu-img, qemu-kvm, qemu-kvm-core, qemu-kvm-tools, qemu-pr-helper, qemu-kvm-common, +16 more Red Hat OpenStack Platform 10 (Newton) qemu-img-rhev, qemu-kvm-rhev, qemu-kvm-tools-rhev, qemu-kvm-common-rhev
    +1 more products
    Red Hat OpenStack Platform 13 (Queens) qemu-img-rhev, qemu-kvm-rhev, qemu-kvm-tools-rhev, qemu-kvm-common-rhev
    not affected: vulnerable code not present

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

0.68% chance of exploitation in the next 30 days, higher than 52% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • gitlab.com https://gitlab.com/qemu-project/qemu/-/issues/782 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

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.