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CVE-2021-3713

25
FAUCET Score

CVE-2021-3713 is an out-of-bounds write vulnerability in the USB Attached SCSI (UAS) device emulation of QEMU, affecting versions prior to 6.2.0-rc0. A malicious guest user can exploit this flaw by providing an unchecked stream number, leading to out-of-bounds access to internal QEMU data structures. This can result in a denial-of-service (crashing QEMU) or potentially arbitrary code execution on the host with the privileges of the QEMU process. Rated with a CVSS score of 7.4 (HIGH), this vulnerability has a low attack complexity and requires local privileges on the guest. There is currently no public exploit code available, nor is there evidence of active exploitation or significant community discussion.

Impacted Technologies

VendorProductVersion(s)CPE
<= 6.1.0CPE matchmatch criteria
cpe:2.3:a:qemu:qemu:*:*:*:*:*:*:*:*
9.0CPE matchmatch criteria
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
10.0CPE matchmatch criteria
cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
11.0CPE matchmatch criteria
cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

7.4HIGH

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

Attack Vector
PHYSICAL
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
CHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
0.7
Impact Score
6.0
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.57%
Probability of exploitation in next 30 days
EPSS Percentile
43.6%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0057 is in the 78th percentile among its peer group of 10 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.0 Bluesky, 0.0 Mastodon, and 0.0 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.2 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (7)

microsoftpatch availablevia msrc
Product: CBL Mariner 1.0 x64Fixed in: 4.2.0-36
microsoftpatch availablevia msrc
Product: 19003-16820Fixed in: 4.2.0-36
microsoftpatch availablevia msrc
Product: 18757-16823Fixed in: 6.2.0-2
microsoftpatch availablevia msrc
Product: cbl2 qemu 6.2.0-2 on CBL Mariner 2.0Fixed in: 6.2.0-2
microsoftpatch availablevia msrc
Product: CBL Mariner 1.0 ARMFixed in: 4.2.0-36
microsoftpatch availablevia msrc
Product: cm1 qemu-kvm 4.2.0-36 on CBL Mariner 1.0Fixed in: 4.2.0-36
redhatpatch availablevia nvd_reference
View patch

Vendor Advisories (3)

microsoft2023-Mar/CVE-2021-3713

CVE-2021-3713

Mar 14, 2023
redhatCVE-2021-3713Low

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

Aug 17, 2021
microsoft2021-Aug/CVE-2021-3713Important

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.

Aug 10, 2021

References

bugzilla.redhat.com / show_bug.cgi
Issue TrackingPatchThird Party Advisory
lists.debian.org / debian-lts-announce/2021/09/msg00000.html
Mailing ListThird Party Advisory
lists.debian.org / debian-lts-announce/2022/09/msg00008.html
Mailing ListThird Party Advisory
security.gentoo.org / glsa/202208-27
Third Party Advisory
security.netapp.com / advisory/ntap-20210923-0006
Third Party Advisory
debian.org / security/2021/dsa-4980
Third Party Advisory