NVD / CVE Program· CNA redhat

CVE-2021-3929: A DMA reentrancy issue was found in the NVM Express Controller (NVME) emulation in QEMU.

Noroxi assessment

Priority: Monitor (action score 32/100)

Public proof-of-concept code exists (GitHub); there is no record of exploitation in the wild.
Probability of exploitation in the next 30 days: 0.67% (FIRST EPSS); higher than 52.3% of all records.
Someone with local access to the system can trigger it. Administrator privileges are required. No user action is required. No special conditions are required; it is repeatable.
Fixed version: qemu (Debian:12) 1:7.0+dfsg-1; qemu (openSUSE:Leap 15.4) 4.2.1-150200.79.1; qemu (openSUSE:Tumbleweed) 6.2.0-44.1.

Low priority for now. Upgrade to qemu (Debian:12) 1:7.0+dfsg-1; qemu (openSUSE:Leap 15.4) 4.2.1-150200.79.1; qemu (openSUSE:Tumbleweed) 6.2.0-44.1 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 DMA reentrancy issue was found in the NVM Express Controller (NVME) emulation in QEMU. This CVE is similar to CVE-2021-3750 and, just like it, when the reentrancy write triggers the reset function nvme_ctrl_reset(), data structs will be freed leading to a use-after-free issue. A malicious guest could use this flaw to crash the QEMU process on the host, resulting in a denial of service condition or, potentially, executing arbitrary code within the context of the QEMU process on the host.

HighCVSS 8.2 · v3.1—Proof of concept Fix available

Published: Aug 25, 2022
Updated: Jun 17, 2026
EPSS: 0.6% · 52th percentile
CWE: CWE-416

Report tools

JSON

Action score

Monitor

Low priority for now.

CVSS: 32 / 40 · 8.2 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 0 / 30 · 0.6%

Get told when this record changes

Not in KEV: no record of exploitation in the wild
Proof of concept exists, no weaponized module
A fix has been released

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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.

Vendor	Product	CPE
qemu	qemu	cpe:2.3:a:qemu:qemu
fedoraproject	fedora	cpe:2.3:o:fedoraproject:fedora

Affected versions

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

fedoraproject fedora35
fedoraproject fedora36
qemu qemubefore 7.0.0

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
- Fixed in qemu-kvm 7.0.0-rc0affected

Package-level exposure

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

Ecosystem	Package	Affected range	Fix
Debian:12	qemu	before 1:7.0+dfsg-1	1:7.0+dfsg-1
openSUSE:Leap 15.4	qemu	before 4.2.1-150200.79.1	4.2.1-150200.79.1
openSUSE:Tumbleweed	qemu	before 6.2.0-44.1	6.2.0-44.1
SUSE:Linux Enterprise High Performance Computing 15 SP1-LTSS	qemu	before 3.1.1.1-150100.80.51.5	3.1.1.1-150100.80.51.5
SUSE:Linux Enterprise High Performance Computing 15 SP2-LTSS	qemu	before 4.2.1-150200.79.1	4.2.1-150200.79.1
SUSE:Linux Enterprise High Performance Computing 15 SP3-ESPOS	qemu	before 5.2.0-150300.121.2	5.2.0-150300.121.2
SUSE:Linux Enterprise Server 12 SP2-BCL	qemu	before 2.6.2-41.76.1	2.6.2-41.76.1
SUSE:Linux Enterprise Server 12 SP5	qemu	before 3.1.1.1-66.1	3.1.1.1-66.1

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-2020-14394Aug 17, 2022 · An infinite loop flaw was found in the USB xHCI controller emulation of QEMU while computing the length of the Transfer Request Block (TRB)
12Monitor
← EarlierCVE-2021-4158Aug 24, 2022 · A NULL pointer dereference issue was found in the ACPI code of QEMU.
24Monitor
Later →CVE-2021-3735Aug 26, 2022 · A deadlock issue was found in the AHCI controller device of QEMU.
17Monitor

Remediation

Which version to upgrade to

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

Product / package	Fixed version	Source
debian:qemu	1:7.0+dfsg-1 · Debian:12	Package registry (OSV)
opensuse:qemu	4.2.1-150200.79.1 · openSUSE:Leap 15.4	Package registry (OSV)
suse:qemu	3.1.1.1-66.1 · SUSE:Linux Enterprise Server 12 SP5	Package registry (OSV)
suse:qemu	4.2.1-150200.79.1 · SUSE:Linux Enterprise High Performance Computing 15 SP2-LTSS	Package registry (OSV)

Exploit status

Proof of concept available

A public proof of concept or detection signature exists. Exploit knowledge is out there; don't delay patching.

Evidence

Proof-of-concept repository on GitHub ×2

Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.

Public exploit evidence
Source	Kind	Date
Proof-of-concept repository on GitHub	stars:171	2022-05-13
Proof-of-concept repository on GitHub	stars:0	2026-10-17

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.

First PoCMay 13, 2022-105 d
PublishedAug 25, 2022
TodayNov 3, 2026+1531 d

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.

qemu-project/qemucommit 736b016

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).

Technical details

Attack conditions

Someone with local access to the system can trigger it.
Administrator privileges are required.
No user action is required.
No special conditions are required; it is repeatable.

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: Local
Attack complexity: Low
Privileges required: High
User interaction: None
Scope: Changed
Confidentiality impact: High
Integrity impact: High
Availability impact: High

Weakness class (CWE)

CWE-416 · Use After Free

CVSS vector

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

nvd-primary

Root cause

After a memory region is freed, another reference pointing to it is still used. By then, the same region may have been allocated for different data.

The bug in code

The whole CWE-416 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

1free(dev->buf);
2/* ... another thread is still running ... */
3process(dev->buf);

Fixed

1lock(&dev->lock);
2free(dev->buf);
3dev->buf = NULL;
4unlock(&dev->lock);

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

Fix✗ → ✓Sep 28, 2026, 10:46 PM UTC

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

References

access.redhat.com/security/cve/CVE-2021-3929

Show all references (5 more)

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

All records