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Fencer Vulns
high 7.4

CVE-2021-3713 json

An out-of-bounds write flaw was found in the UAS (USB Attached SCSI) device emulation of QEMU in versions prior to 6.2.0-rc0.

published 2021-08-25 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-26994

cvss
7.4
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 47%
public exploits
0
none known

Summary

An out-of-bounds write flaw was found in the UAS (USB Attached SCSI) device emulation of QEMU in versions prior to 6.2.0-rc0. The device uses the guest supplied stream number unchecked, which can lead to out-of-bounds access to the UASDevice->data3 and UASDevice->status3 fields. A malicious guest user could use this flaw to crash QEMU or potentially achieve code execution with the privileges of the QEMU process on the host.

Patch / fix

  • qemu Debian 14, Debian 13, Debian 12 1:6.1+dfsg-2

debian advisories DEBIAN-CVE-2021-3713

  • qemu Ubuntu 22.04 LTS 1:6.2+dfsg-2ubuntu5

ubuntu advisories UBUNTU-CVE-2021-3713

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 12 SP3, SLES 12 SP3-LTSS, SLES 12 SP3-BCL +3 more 2.9.1-43.62.1
  • qemu SLES for SAP 12 SP4, SLES 12 SP4-LTSS, OpenStack Cloud Crowbar 9 +1 more 2.11.2-5.40.2
  • qemu SLES for SAP 15 SP1, SLES 15 SP1-LTSS, SLES 15 SP1-BCL +3 more 3.1.1.1-80.40.1
  • qemu SLES for SAP 15, SLES 15-LTSS, SLE High Performance Computing 15-LTSS +1 more 2.11.2-70.59.1
  • qemu SLE Module for Server Applications 15 SP3, SLE Module for Basesystem 15 SP3, SLE Micro 5.1 5.2.0-106.4
  • qemu SLE Module for Server Applications 15 SP2, SLE Module for Basesystem 15 SP2, SLE Micro 5.0 4.2.1-11.31.3
  • qemu SLES for SAP 12 SP5, SLES 12 SP5 3.1.1.1-60.2

suse advisories SUSE-SU-2021:3653-1SUSE-SU-2021:3635-1SUSE-SU-2021:3614-1SUSE-SU-2021:3613-1SUSE-SU-2021:3605-1SUSE-SU-2021:3604-1

  • qemu openSUSE Tumbleweed 6.1.0-34.1
  • qemu openSUSE Leap 15.2 4.2.1-lp152.9.23.1
  • qemu-testsuite openSUSE Leap 15.2 4.2.1-lp152.9.23.1
  • qemu-linux-user openSUSE Leap 15.2 4.2.1-lp152.9.23.1
  • qemu openSUSE Leap 15.3 3.1.1.1-80.40.1
  • qemu openSUSE Leap 15.3 5.2.0-106.4
  • qemu-testsuite openSUSE Leap 15.3 5.2.0-106.3
  • qemu-linux-user openSUSE Leap 15.3 5.2.0-106.3

opensuse advisories openSUSE-SU-2024:11597-1openSUSE-SU-2021:1461-1openSUSE-SU-2021:3614-1openSUSE-SU-2021:3605-1openSUSE-SU-2021:3604-1

  • qemu Alpine 3.15 6.1.1-r0

alpine advisories ALPINE-CVE-2021-3713

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • qemu CBL-Mariner 2.0 6.2.0-2

azure linux advisories AZL-6831

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-2021-3713 updated cvss 7.8

QEMU: out-of-bounds write in UAS (USB Attached SCSI) device emulation

  • 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-img-rhev, +9 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

0.57% chance of exploitation in the next 30 days, higher than 47% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 7.4 CVSS:3.1/AV:P/AC:L/PR:L/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.