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Full vulnerability report · 2022
CVE-2021-3735High confidence

A privileged user inside the guest could use this flaw to hang the QEMU process on the host, resulting in a denial of service condition

n/a · QEMU

4.4MediumCVSS 3.1
Recommended action
Scheduled

Medium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority.

Fix not verified
Distribution package intelligence

Ubuntu vendor package status

Canonical’s release and source-package findings are shown separately from local repository availability.

1 package state
Repository candidate not checked

A published vendor fix does not prove that a matching update is enabled and installable on a particular asset. Confirm the local package candidate before scheduling remediation.

Ubuntu releaseSource packageVendor stateFixed versionEvidence
Ubuntu 24.04 LTSnoble · standard archiveqemuUnder evaluationCanonical reports that the package might be affected and still needs evaluation or fixing.Not published in this feedCanonical record ↗Source updated 9 Sept 2026
Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Select the national-authority views to include. The exact source language is shown on each matched advisory. Your choice is remembered on this device and encoded in the shareable URL.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2021-27011

No EUVD known-exploited evidence

ENISA has published the identifier mapping but no EUVD description has been stored yet.

EUVD state
Present in the current official mapping
Known exploitation
Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score
Not supplied in the stored EUVD record
Advisory evidence
No linked advisory details stored yet
Recommended actionScheduled

Medium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority.

Fix not verified
01

What, why and how

A deadlock issue was found in the AHCI controller device of QEMU. It occurs on a software reset (ahci_reset_port) while handling a host-to-device Register FIS (Frame Information Structure) packet from the guest. A privileged user inside the guest could use this flaw to hang the QEMU process on the host, resulting in a denial of service condition. The highest threat from this vulnerability is to system availability.

What

A deadlock issue was found in the AHCI controller device of QEMU. It occurs on a software reset (ahci_reset_port) while handling a host-to-device Register FIS (Frame Information Structure) packet from the guest. A privileged user inside the guest could use this flaw to hang the QEMU process on the host, resulting in a denial of service condition. The highest threat from this vulnerability is to system availability.

Why

The product does not properly acquire or release a lock on a resource, leading to unexpected resource state changes and behaviors.

How

An attacker operating through local access may attempt exploitation with elevated privileges. If successful, the issue may disrupt the affected service.

What

A deadlock issue was found in the AHCI controller device of QEMU. It occurs on a software reset (ahci_reset_port) while handling a host-to-device Register FIS (Frame Information Structure) packet from the guest. A privileged user inside the guest could use this flaw to hang the QEMU process on the host, resulting in a denial of service condition. The highest threat from this vulnerability is to system availability.

Why

The product does not properly acquire or release a lock on a resource, leading to unexpected resource state changes and behaviors.

How

An attacker operating through local access may attempt exploitation with elevated privileges. If successful, the issue may disrupt the affected service.

02

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
No confirmed evidence

No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
None recorded

No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.

Likely attack path
local access → Improper Locking → disrupt the affected service
Attack surface
Local
Privileges required
High: elevated access is required
User interaction
None
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Unchanged: impact remains within the vulnerable component's security authority
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-667

CWE-667: Improper Locking. The product does not properly acquire or release a lock on a resource, leading to unexpected resource state changes and behaviors.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H

Common Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.

AVLocalAttack vector: The attacker needs local access to the vulnerable system.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRHighPrivileges required: The attacker needs elevated or administrative privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CNoneConfidentiality impact: No direct loss is represented by this metric.INoneIntegrity impact: No direct loss is represented by this metric.AHighAvailability impact: A successful attack can cause a major loss.
Post-exploitation / living off the land
The issue can support a local privilege or sandbox boundary transition; normal system utilities may then be available in the gained context.
Denial of serviceCWE-667
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

CERT-FR · French · CERTFR-2026-AVI-0326Multiples vulnérabilités dans les produits VMware

ord?id=CVE-2021-31879 Référence CVE CVE-2021-33096 https://www.cve.org/CVERecord?id=CVE-2021-33096 Référence CVE CVE-2021-33110 https://www.cve.org/CVERecord?id=CVE-2021-33110 Référence CVE CVE-2021-33113 https://www.cve.org/CVERecord?id=CVE-2021-33113 Référence CVE CVE-2021-33114 https://www.cve.org/CVERecord?id=CVE-2021-33114 Référence CVE CVE-2021-33115 https://www.cve.org/CVERecord?id=CVE-2021-33115 Référence CVE CVE-2021-33139 https://www.cve.org/CVERecord?id=CVE-2021-33139 Référence CVE CVE-2021-33155 https://www.cve.org/CVERecord?id=CVE-2021-33155 Référence CVE CVE-2021-3714 https://www.cve.org/CVERecord?id=CVE-2021-3714 Référence CVE CVE-2021-3735 https://www.cve.org/CVERecord?id=CVE-2021-3735 Référence CVE CVE-2021-3773 https://www.cve.org/CVERecord?id=CVE-2021-3773 Référence CVE CVE-2021-3826 https://www.cve.org/CVERecord?id=CVE-2021-3826 Référence CVE CVE-2021-3864 https://www.cve.org/CVERecord?id=CVE-2021-3864 Référence CVE CVE-2021-4095 https://www.cve.org/CVERecord?id=CVE-2021-4095 Référence CVE CVE-2021-42771 https://www.cve.org/CVERecord?id=CVE-2021-42771 Référence CVE CVE-2021-44532 https://www.cve.org/CVERecord?id=CVE-2021-44532 Référence CVE CVE-2021-44534 https://www.cve.org/CVERecord?id=CVE-2021-44534 Référence CVE CVE-2021-45261 https://www.cve.org/CVERecord?id=CVE-2021-

Official advisory
CERT-FR · French · CERTFR-2026-AVI-0316Multiples vulnérabilités dans les produits VMware

ord?id=CVE-2021-31879 Référence CVE CVE-2021-33096 https://www.cve.org/CVERecord?id=CVE-2021-33096 Référence CVE CVE-2021-33110 https://www.cve.org/CVERecord?id=CVE-2021-33110 Référence CVE CVE-2021-33113 https://www.cve.org/CVERecord?id=CVE-2021-33113 Référence CVE CVE-2021-33114 https://www.cve.org/CVERecord?id=CVE-2021-33114 Référence CVE CVE-2021-33115 https://www.cve.org/CVERecord?id=CVE-2021-33115 Référence CVE CVE-2021-33139 https://www.cve.org/CVERecord?id=CVE-2021-33139 Référence CVE CVE-2021-33155 https://www.cve.org/CVERecord?id=CVE-2021-33155 Référence CVE CVE-2021-3714 https://www.cve.org/CVERecord?id=CVE-2021-3714 Référence CVE CVE-2021-3735 https://www.cve.org/CVERecord?id=CVE-2021-3735 Référence CVE CVE-2021-3773 https://www.cve.org/CVERecord?id=CVE-2021-3773 Référence CVE CVE-2021-3826 https://www.cve.org/CVERecord?id=CVE-2021-3826 Référence CVE CVE-2021-3864 https://www.cve.org/CVERecord?id=CVE-2021-3864 Référence CVE CVE-2021-4095 https://www.cve.org/CVERecord?id=CVE-2021-4095 Référence CVE CVE-2021-42771 https://www.cve.org/CVERecord?id=CVE-2021-42771 Référence CVE CVE-2021-44532 https://www.cve.org/CVERecord?id=CVE-2021-44532 Référence CVE CVE-2021-44534 https://www.cve.org/CVERecord?id=CVE-2021-44534 Référence CVE CVE-2021-45261 https://www.cve.org/CVERecord?id=CVE-2021-

Official advisory
03

Patch and workaround

Operational remediation based on structured source evidence.

Status
?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Fix not verified
Affected
Not Known
Fixed
No fixed version is explicitly recorded in the structured CVE data.
Action
No verified patch reference is present in the current structured sources. Check the vendor advisory before making a change.
Workaround
No verified workaround is recorded. Limit untrusted access and use least privilege until authoritative guidance is available.
04

Evidence and provenance

Published 26 Aug 2022 · Last source change 28 Feb 2025, 13:07 UTC · CWE-667 · Improper Locking

CVE recordCVE.org · 5.1
CVSS sourceNIST NVD
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-08-14
European sourceENISA EUVD · EUVD-2021-27011
Product sourceCNA
Remediation sourceCVE/CNA references
CWE sourceCNA
NVD statusNVD modified after enrichment

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates →

No material field changes have been recorded since change tracking began. Routine source refreshes and cosmetic edits are intentionally excluded.

Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
Free version - for non-commercial use only.CVE-2021-3735 · cve.blacktree.nl