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CVE-2021-3930

22
FAUCET Score

CVE-2021-3930 is an off-by-one error in QEMU's SCSI device emulation, specifically affecting Debian, QEMU, and Red Hat products. This vulnerability, rated Medium severity (CVSS 6.5), allows a malicious guest to trigger a denial of service by crashing QEMU through a specially crafted MODE SELECT command. There is currently no evidence of active exploitation, publicly available exploit code, or significant community discussion surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
< 6.2.0CPE matchmatch criteria
cpe:2.3:a:qemu:qemu:*:*:*:*:*:*:*:*
8.0CPE matchmatch criteria
cpe:2.3:a:redhat:codeready_linux_builder:8.0:*:*:*:*:*:*:*
8.0CPE matchmatch criteria
cpe:2.3:a:redhat:codeready_linux_builder_for_ibm_z_systems:8.0:*:*:*:*:*:*:*
8.0CPE matchmatch criteria
cpe:2.3:a:redhat:codeready_linux_builder_for_power_little_endian:8.0:*:*:*:*:*:*:*
10CPE matchmatch criteria
cpe:2.3:a:redhat:openstack:10:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

6.5MEDIUM

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

Attack Vector
LOCAL
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
CHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
2.0
Impact Score
4.0
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.34%
Probability of exploitation in next 30 days
EPSS Percentile
26.3%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0034 is in the 83rd percentile among its peer group of 15,938 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.0 Bluesky, 0.0 Mastodon, and 0.1 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (15)

microsoftpatch availablevia msrc
Product: 18756-16820Fixed in: 4.2.0-38
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: cm1 qemu-kvm 4.2.0-38 on CBL Mariner 1.0Fixed in: 4.2.0-38
microsoftpatch availablevia msrc
Product: CBL Mariner 1.0 x64Fixed in: 4.2.0-38
microsoftpatch availablevia msrc
Product: CBL Mariner 1.0 ARMFixed in: 4.2.0-38
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 8Fixed in: virt:rhel-8050020211203195115.c5368500
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 8Fixed in: virt-devel:rhel-8050020211203195115.c5368500
View patch
redhatpatch availablevia redhat_api
Product: Advanced Virtualization for RHEL 8.4.0.EUSFixed in: virt:av-8040020211126213321.522a0ee4
View patch
redhatpatch availablevia redhat_api
Product: Advanced Virtualization for RHEL 8.4.0.EUSFixed in: virt-devel:av-8040020211126213321.522a0ee4
View patch
redhatpatch availablevia redhat_api
Product: Advanced Virtualization for RHEL 8.5.0.ZFixed in: virt:av-8050020211203164130.c5368500
View patch
redhatpatch availablevia redhat_api
Product: Advanced Virtualization for RHEL 8.5.0.ZFixed in: virt-devel:av-8050020211203164130.c5368500
View patch
redhatpatch availablevia nvd_reference
View patch
redhatno patchvia redhat_api
Product: Red Hat Enterprise Linux 8 Advanced VirtualizationFixed in: virt:av/qemu-kvm
redhatend of lifevia redhat_api
Product: Red Hat Enterprise Linux 8 Advanced VirtualizationFixed in: virt:8.2/qemu-kvm

Vendor Advisories (3)

microsoft2023-Mar/CVE-2021-3930

CVE-2021-3930

Mar 14, 2023
microsoft2022-Feb/CVE-2021-3930Moderate

An off-by-one error was found in the SCSI device emulation in QEMU. It could occur while processing MODE SELECT commands in mode_sense_page() if the 'page' argument was set to MODE_PAGE_ALLS (0x3f). A malicious guest could use this flaw to potentially crash QEMU resulting in a denial of service condition.

Feb 8, 2022
redhatCVE-2021-3930Low

QEMU: off-by-one error in mode_sense_page() in hw/scsi/scsi-disk.c

Feb 4, 2021

References

bugzilla.redhat.com / show_bug.cgi
Issue TrackingPatchVendor Advisory
lists.debian.org / debian-lts-announce/2022/04/msg00002.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-20220225-0007
Third Party Advisory