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CVE-2021-3608

21
FAUCET Score

CVE-2021-3608 describes a flaw in QEMU's implementation of VMWare's paravirtual RDMA device, affecting versions prior to 6.1.0, including various Debian and Fedora distributions. This vulnerability stems from improper handling of a "PVRDMA_REG_DSRHIGH" write from a guest, leading to the access of an uninitialized pointer. With a CVSS score of 6.0 (Medium), it primarily poses a threat to system availability, potentially causing QEMU to crash or exhibit undefined behavior. There is currently no evidence of active exploitation, public exploit code, or significant community discussion surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
< 6.1.0CPE matchmatch criteria
cpe:2.3:a:qemu:qemu:*:*:*:*:*:*:*:*
10.0CPE matchmatch criteria
cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
34CPE matchmatch criteria
cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

6.0MEDIUM

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

Attack Vector
LOCAL
Attack Complexity
LOW
Privileges Required
HIGH
User Interaction
NONE
Scope
CHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
1.5
Impact Score
4.0
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.36%
Probability of exploitation in next 30 days
EPSS Percentile
28.9%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0036 is in the 77th percentile among its peer group of 3,720 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 (4)

microsoftpatch availablevia msrc
Product: 18756-16820Fixed 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
microsoftpatch availablevia msrc
Product: cm1 qemu-kvm 4.2.0-38 on CBL Mariner 1.0Fixed in: 4.2.0-38

Vendor Advisories (3)

microsoft2022-Mar/CVE-2021-3608

CVE-2021-3608

Mar 8, 2022
microsoft2022-Feb/CVE-2021-3608Moderate

A flaw was found in the QEMU implementation of VMWare's paravirtual RDMA device in versions prior to 6.1.0. The issue occurs while handling a "PVRDMA_REG_DSRHIGH" write from the guest and may result in a crash of QEMU or cause undefined behavior due to the access of an uninitialized pointer. The highest threat from this vulnerability is to system availability.

Feb 8, 2022
redhatCVE-2021-3608Low

QEMU: pvrdma: uninitialized memory unmap in pvrdma_ring_init()

Jun 17, 2021

References

bugzilla.redhat.com / show_bug.cgi
Issue TrackingThird Party Advisory
lists.debian.org / debian-lts-announce/2022/09/msg00008.html
Mailing ListThird Party Advisory
lists.gnu.org / archive/html/qemu-devel/2021-06/msg07926.html
Mailing ListPatchThird Party Advisory
security.gentoo.org / glsa/202208-27
Third Party Advisory
security.netapp.com / advisory/ntap-20220318-0002
Third Party Advisory