HOMEVULNERABILITIESCVE-2021-3713
HIGH

CVE-2021-3713

CWE-787Published: August 25, 2021· Updated: Jun 17, 2026

7.4
CVSS v3.1

Official Description

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.

NVD Source

Technical Analysis

CVE-2021-3713 requires local access, meaning attackers must already have a foothold on the target system.

Exploitation requires low privileges, which limits the exposure to scenarios where an attacker has already gained initial access.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 7.4.

The vulnerability has a "Changed" scope, meaning successful exploitation can impact components beyond the vulnerable component itself — such as the host operating system or adjacent services.

From a weakness classification perspective (CWE-787): Out-of-bounds write vulnerabilities can lead to data corruption, crashes, or arbitrary code execution.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorPhysical
Attack ComplexityLow
Privileges Req.Low
User InteractionNone
ScopeChanged
Impact
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:P/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Affected Vendors & Products

Debian1 product(s)
debian linux
qemu1 product(s)
qemu
Source: NVD CPE · 4 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
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Official Patches & Advisories

All References (12)

Quick Facts

CVE IDCVE-2021-3713
CVSS Score7.4 / 10
SeverityHIGH
WeaknessCWE-787
CISA KEVNo
Affected2 vendor(s)
PublishedAug 25, 2021

Related CVEs (CWE-787)

Recommended Actions

  • Apply vendor patches immediately
  • Monitor CVE-2021-3713 in threat intel feeds
  • Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWATCH.COM. CVE data is provided under the NVD usage policy.