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NVD / CVE Program· CNA redhat

CVE-2021-3682: A flaw was found in the USB redirector device emulation of QEMU in versions prior to 6.1.0-rc2.

Noroxi assessment

Priority: Monitor (action score 35/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 2.8% (FIRST EPSS); higher than 86.8% of all records.
  • Anyone who can reach it over the internet can trigger it. A low-privileged account is enough. No user action is required. Special conditions such as timing or configuration are required.
  • Fixed version: hivex (AlmaLinux:8) 1.3.18-23.module_el8.6.0+2880+7d9e3703; hivex-devel (AlmaLinux:8) 1.3.18-23.module_el8.6.0+2880+7d9e3703; libguestfs (AlmaLinux:8) 1:1.44.0-5.module_el8.6.0+2880+7d9e3703.alma.
  • Mentioned 2 times in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to hivex (AlmaLinux:8) 1.3.18-23.module_el8.6.0+2880+7d9e3703; hivex-devel (AlmaLinux:8) 1.3.18-23.module_el8.6.0+2880+7d9e3703; libguestfs (AlmaLinux:8) 1:1.44.0-5.module_el8.6.0+2880+7d9e3703.alma or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

A flaw was found in the USB redirector device emulation of QEMU in versions prior to 6.1.0-rc2. It occurs when dropping packets during a bulk transfer from a SPICE client due to the packet queue being full. A malicious SPICE client could use this flaw to make QEMU call free() with faked heap chunk metadata, resulting in a crash of QEMU or potential code execution with the privileges of the QEMU process on the host.

HighCVSS 8.5 · v3.1—No exploit Fix available
Published
Aug 5, 2021
Updated
Jun 17, 2026
EPSS
2.8% · 86th percentile

Report tools

JSON

Action score

35

Monitor

Low priority for now.

CVSS
34 / 40 · 8.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
1 / 30 · 2.8%

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  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

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  • when exploit code appears or is weaponized
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  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
qemuqemu
redhatenterprise linux
debiandebian linux

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • debian debian linux10.0
  • debian debian linux11.0
  • debian debian linux9.0
  • qemu qemubefore 6.1.0
  • qemu qemu6.1.0
  • redhat enterprise linux8.0

Versions reported by the vendor

Affected version ranges reported by the assigning authority (redhat). Independent of NVD's CPE analysis and usually ahead of it.

  • n/a QEMU

    • qemu 6.1.0-rc2affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
AlmaLinux:8hivexbefore 1.3.18-23.module_el8.6.0+2880+7d9e37031.3.18-23.module_el8.6.0+2880+7d9e3703
AlmaLinux:8hivex-develbefore 1.3.18-23.module_el8.6.0+2880+7d9e37031.3.18-23.module_el8.6.0+2880+7d9e3703
AlmaLinux:8libguestfsbefore 1:1.44.0-5.module_el8.6.0+2880+7d9e3703.alma1:1.44.0-5.module_el8.6.0+2880+7d9e3703.alma
AlmaLinux:8libguestfs-appliancebefore 1:1.44.0-5.module_el8.6.0+2880+7d9e3703.alma1:1.44.0-5.module_el8.6.0+2880+7d9e3703.alma
AlmaLinux:8libguestfs-bash-completionbefore 1:1.44.0-5.module_el8.6.0+2880+7d9e3703.alma1:1.44.0-5.module_el8.6.0+2880+7d9e3703.alma
AlmaLinux:8libguestfs-develbefore 1:1.44.0-5.module_el8.6.0+2880+7d9e3703.alma1:1.44.0-5.module_el8.6.0+2880+7d9e3703.alma
AlmaLinux:8libguestfs-gfs2before 1:1.44.0-5.module_el8.6.0+2880+7d9e3703.alma1:1.44.0-5.module_el8.6.0+2880+7d9e3703.alma
AlmaLinux:8libguestfs-gobjectbefore 1:1.44.0-5.module_el8.6.0+2880+7d9e3703.alma1:1.44.0-5.module_el8.6.0+2880+7d9e3703.alma
AlmaLinux:8libguestfs-gobject-develbefore 1:1.44.0-5.module_el8.6.0+2880+7d9e3703.alma1:1.44.0-5.module_el8.6.0+2880+7d9e3703.alma
AlmaLinux:8libguestfs-inspect-iconsbefore 1:1.44.0-5.module_el8.6.0+2880+7d9e3703.alma1:1.44.0-5.module_el8.6.0+2880+7d9e3703.alma
AlmaLinux:8libguestfs-javabefore 1:1.44.0-5.module_el8.6.0+2880+7d9e3703.alma1:1.44.0-5.module_el8.6.0+2880+7d9e3703.alma
AlmaLinux:8libguestfs-java-develbefore 1:1.44.0-5.module_el8.6.0+2880+7d9e3703.alma1:1.44.0-5.module_el8.6.0+2880+7d9e3703.alma
AlmaLinux:8libguestfs-javadocbefore 1:1.44.0-5.module_el8.6.0+2880+7d9e3703.alma1:1.44.0-5.module_el8.6.0+2880+7d9e3703.alma
AlmaLinux:8libguestfs-man-pages-jabefore 1:1.44.0-5.module_el8.6.0+2880+7d9e3703.alma1:1.44.0-5.module_el8.6.0+2880+7d9e3703.alma
AlmaLinux:8libguestfs-man-pages-ukbefore 1:1.44.0-5.module_el8.6.0+2880+7d9e3703.alma1:1.44.0-5.module_el8.6.0+2880+7d9e3703.alma
AlmaLinux:8libguestfs-rescuebefore 1:1.44.0-5.module_el8.6.0+2880+7d9e3703.alma1:1.44.0-5.module_el8.6.0+2880+7d9e3703.alma
AlmaLinux:8libguestfs-rsyncbefore 1:1.44.0-5.module_el8.6.0+2880+7d9e3703.alma1:1.44.0-5.module_el8.6.0+2880+7d9e3703.alma
AlmaLinux:8libguestfs-toolsbefore 1:1.44.0-5.module_el8.6.0+2880+7d9e3703.alma1:1.44.0-5.module_el8.6.0+2880+7d9e3703.alma
AlmaLinux:8libguestfs-tools-cbefore 1:1.44.0-5.module_el8.6.0+2880+7d9e3703.alma1:1.44.0-5.module_el8.6.0+2880+7d9e3703.alma
AlmaLinux:8libguestfs-winsupportbefore 8.6-1.module_el8.6.0+2880+7d9e37038.6-1.module_el8.6.0+2880+7d9e3703
AlmaLinux:8libguestfs-xfsbefore 1:1.44.0-5.module_el8.6.0+2880+7d9e3703.alma1:1.44.0-5.module_el8.6.0+2880+7d9e3703.alma
AlmaLinux:8libiscsibefore 1.18.0-8.module_el8.6.0+2880+7d9e37031.18.0-8.module_el8.6.0+2880+7d9e3703
AlmaLinux:8libiscsi-develbefore 1.18.0-8.module_el8.6.0+2880+7d9e37031.18.0-8.module_el8.6.0+2880+7d9e3703
AlmaLinux:8libiscsi-utilsbefore 1.18.0-8.module_el8.6.0+2880+7d9e37031.18.0-8.module_el8.6.0+2880+7d9e3703

+96

Same product

qemu: all records

Other highest-scoring records for the same primary product.

  • CVE-2019-12928The QMP migrate command in QEMU version 4.0.0 and earlier is vulnerable to OS command injection, which allows the remote attacker to achieve
    60This week
  • CVE-2015-8556Local privilege escalation vulnerability in the Gentoo QEMU package before 2.5.0-r1.
    44Plan
  • CVE-2017-15118A stack-based buffer overflow vulnerability was found in NBD server implementation in qemu before 2.11 allowing a client to request an expor
    43Plan

Published before and after this one in the same product

  • ← EarlierCVE-2019-12067Jun 2, 2021 · The ahci_commit_buf function in ide/ahci.c in QEMU allows attackers to cause a denial of service (NULL dereference) when the command header
    26Monitor
  • ← EarlierCVE-2020-27661Jun 2, 2021 · A divide-by-zero issue was found in dwc2_handle_packet in hw/usb/hcd-dwc2.c in the hcd-dwc2 USB host controller emulation of QEMU.
    26Monitor
  • Later →CVE-2021-3713Aug 25, 2021 · 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.
    29Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
almalinux:hivex1.3.18-23.module_el8.6.0+2880+7d9e3703 · AlmaLinux:8Package registry (OSV)
almalinux:hivex-devel1.3.18-23.module_el8.6.0+2880+7d9e3703 · AlmaLinux:8Package registry (OSV)
almalinux:libguestfs1:1.44.0-5.module_el8.6.0+2880+7d9e3703.alma · AlmaLinux:8Package registry (OSV)
almalinux:libguestfs-appliance1:1.44.0-5.module_el8.6.0+2880+7d9e3703.alma · AlmaLinux:8Package registry (OSV)
almalinux:libguestfs-bash-completion1:1.44.0-5.module_el8.6.0+2880+7d9e3703.alma · AlmaLinux:8Package registry (OSV)
almalinux:libguestfs-devel1:1.44.0-5.module_el8.6.0+2880+7d9e3703.alma · AlmaLinux:8Package registry (OSV)
almalinux:libguestfs-gfs21:1.44.0-5.module_el8.6.0+2880+7d9e3703.alma · AlmaLinux:8Package registry (OSV)
almalinux:libguestfs-gobject1:1.44.0-5.module_el8.6.0+2880+7d9e3703.alma · AlmaLinux:8Package registry (OSV)
almalinux:libguestfs-gobject-devel1:1.44.0-5.module_el8.6.0+2880+7d9e3703.alma · AlmaLinux:8Package registry (OSV)
almalinux:libguestfs-inspect-icons1:1.44.0-5.module_el8.6.0+2880+7d9e3703.alma · AlmaLinux:8Package registry (OSV)
almalinux:libguestfs-java1:1.44.0-5.module_el8.6.0+2880+7d9e3703.alma · AlmaLinux:8Package registry (OSV)
almalinux:SLOF20210217-1.module_el8.6.0+2880+7d9e3703 · AlmaLinux:8Package registry (OSV)
debian:qemu1:6.0+dfsg-3 · Debian:12Package registry (OSV)
opensuse:qemu4.2.1-lp152.9.20.1 · openSUSE:Leap 15.2Package registry (OSV)
opensuse:qemu-linux-user4.2.1-lp152.9.20.1 · openSUSE:Leap 15.2Package registry (OSV)
opensuse:qemu-testsuite4.2.1-lp152.9.20.1 · openSUSE:Leap 15.2Package registry (OSV)
red hat:hivex0:1.3.18-21.module+el8.4.0+11609+2eba841a · Red Hat:advanced_virtualization:8.4::el8Package registry (OSV)
red hat:hivex-debuginfo0:1.3.18-21.module+el8.4.0+11609+2eba841a · Red Hat:advanced_virtualization:8.4::el8Package registry (OSV)
red hat:hivex-debugsource0:1.3.18-21.module+el8.4.0+11609+2eba841a · Red Hat:advanced_virtualization:8.4::el8Package registry (OSV)
red hat:hivex-devel0:1.3.18-21.module+el8.4.0+11609+2eba841a · Red Hat:advanced_virtualization:8.4::el8Package registry (OSV)
red hat:libguestfs1:1.44.0-2.module+el8.4.0+10146+75917d2f · Red Hat:advanced_virtualization:8.4::el8Package registry (OSV)
red hat:libguestfs-bash-completion1:1.44.0-2.module+el8.4.0+10146+75917d2f · Red Hat:advanced_virtualization:8.4::el8Package registry (OSV)
red hat:libguestfs-debuginfo1:1.44.0-2.module+el8.4.0+10146+75917d2f · Red Hat:advanced_virtualization:8.4::el8Package registry (OSV)
red hat:libguestfs-debugsource1:1.44.0-2.module+el8.4.0+10146+75917d2f · Red Hat:advanced_virtualization:8.4::el8Package registry (OSV)
red hat:libguestfs-devel1:1.44.0-2.module+el8.4.0+10146+75917d2f · Red Hat:advanced_virtualization:8.4::el8Package registry (OSV)
red hat:libguestfs-gfs21:1.44.0-2.module+el8.4.0+10146+75917d2f · Red Hat:advanced_virtualization:8.4::el8Package registry (OSV)
red hat:libguestfs-gobject1:1.44.0-2.module+el8.4.0+10146+75917d2f · Red Hat:advanced_virtualization:8.4::el8Package registry (OSV)
red hat:SLOF0:20200717-1.gite18ddad8.module+el8.4.0+8855+a9e237a9 · Red Hat:advanced_virtualization:8.4::el8Package registry (OSV)
suse:qemu4.2.1-11.28.1 · SUSE:Linux Enterprise Module for Basesystem 15 SP2Package registry (OSV)
suse:xen4.4.4_50-61.67.1 · SUSE:Linux Enterprise Server 11 SP4-LTSSPackage registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • Special conditions such as timing or configuration are required.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted

Impact can extend beyond the vulnerable component (scope changes).

Attack vector
Network
Attack complexity
High
Privileges required
Low
User interaction
None
Scope
Changed
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-763 · Release of Invalid Pointer or Reference

CVSS vector

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (5 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records