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Full vulnerability report · 2021
CVE-2021-42284High confidence

Windows Hyper-V Denial of Service Vulnerability

Microsoft · Windows 10 Version 1507

6.8MediumCVSS 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.

Patch available
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityMediumOperational priority:Medium, unchanged from published severity.unchanged

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • EPSS is 3.73% for the current model date.

Compensating controls

  • Validate the affected product branch and deploy the verified fixed release.
  • Restrict local access and enforce least privilege on affected hosts.
  • Monitor vendor guidance and exploitation sources for a material change.

Verification

  1. Confirm that the asset runs Microsoft Windows 10 Version 1507 and falls inside the recorded affected range.
  2. Verify the installed build against the product-specific fixed version after deployment.
  3. Validate exposure, authentication requirements and compensating controls in the actual environment.
  4. Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Mitigation target: As exposure requiresRemediation target: Within 365 days

This automated reassessment organises public evidence. It does not know asset exposure, business impact or control effectiveness and does not replace CVSS or a human risk decision.

Optional official sources

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

Choose official national sources for this report. Each advisory shows its original language. Your selection is remembered on this device and included in shared links.

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-2021-29259

No EUVD known-exploited evidence

Windows Hyper-V Denial of Service Vulnerability

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
6.8 · CVSS 3.1
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.

Patch available
01

What, why and how

Windows Hyper-V Denial of Service Vulnerability

What

Windows Hyper-V Denial of Service Vulnerability

Why

The current structured CVE record identifies a security weakness, but the root cause requires confirmation in the linked vendor material.

How

An attacker operating through an adjacent network may attempt exploitation with low privileges. If successful, the issue may disrupt the affected service.

What

Windows Hyper-V Denial of Service Vulnerability

Why

The current structured CVE record identifies a security weakness, but the root cause requires confirmation in the linked vendor material.

How

An attacker operating through an adjacent network may attempt exploitation with low 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
an adjacent network → vulnerable operation → disrupt the affected service
Attack surface
Adjacent
Privileges required
Low: a basic authenticated account is required
User interaction
None
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Changed: exploitation can affect a different security authority
Weakness
?CWE means Common Weakness Enumeration.
CWE not yet assigned
CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H/E:P/RL:O/RC:C

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

AVAdjacentAttack vector: The attacker must be on an adjacent or logically close network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRLowPrivileges required: The attacker needs basic user-level privileges.UINoneUser interaction: No action by another user is required.SChangedScope: The attack can affect a component governed by a different security 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
No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
Denial of service
A

Official authority intelligence

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

ENISA EUVD · EUVD-2021-29259Official EUVD mapping

Windows Hyper-V Denial of Service Vulnerability

Official EUVD record ↗
Cyber Security Agency of Singapore · English · CSA-SB-20211117Security Bulletin 17 Nov 2021

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 17 Nov 2021, published on 17 November 2021. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
CERT-FR · French · CERTFR-2021-AVI-862Multiples vulnérabilités dans Microsoft Windows

d?id=CVE-2021-42274 Référence CVE CVE-2021-42275 https://www.cve.org/CVERecord?id=CVE-2021-42275 Référence CVE CVE-2021-42276 https://www.cve.org/CVERecord?id=CVE-2021-42276 Référence CVE CVE-2021-42277 https://www.cve.org/CVERecord?id=CVE-2021-42277 Référence CVE CVE-2021-42278 https://www.cve.org/CVERecord?id=CVE-2021-42278 Référence CVE CVE-2021-42279 https://www.cve.org/CVERecord?id=CVE-2021-42279 Référence CVE CVE-2021-42280 https://www.cve.org/CVERecord?id=CVE-2021-42280 Référence CVE CVE-2021-42282 https://www.cve.org/CVERecord?id=CVE-2021-42282 Référence CVE CVE-2021-42283 https://www.cve.org/CVERecord?id=CVE-2021-42283 Référence CVE CVE-2021-42284 https://www.cve.org/CVERecord?id=CVE-2021-42284 Référence CVE CVE-2021-42285 https://www.cve.org/CVERecord?id=CVE-2021-42285 Référence CVE CVE-2021-42286 https://www.cve.org/CVERecord?id=CVE-2021-42286 Référence CVE CVE-2021-42287 https://www.cve.org/CVERecord?id=CVE-2021-42287 Référence CVE CVE-2021-42288 https://www.cve.org/CVERecord?id=CVE-2021-42288 Référence CVE CVE-2021-42291 https://www.cve.org/CVERecord?id=CVE-2021-42291 Référence CVE CVE-2021-42297 https://www.cve.org/CVERecord?id=CVE-2021-42297 Gestion détaillée du document le 10 novembre 2021 Version initiale le 16 novembre 2021 ajout de CVE-2021-42297 Alertes Avis Bulletins d’act

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2021-004132複数の Microsoft Windows 製品におけるサービス運用妨害 (DoS) の脆弱性

複数の Microsoft Windows 製品には、Windows Hyper-V に不備があるため、サービス運用妨害 (DoS) の脆弱性が存在します。

Official advisory ↗
KISA KrCERT/CC · Korean · KNVD-5435MS 11월 보안 위협에 따른 정기 보안 업데이트 권고

취약성 Microsoft Exchange Server CVE-2021-42305 Microsoft Exchange Server 스푸핑 취약성 Microsoft Exchange Server CVE-2021-41349 Microsoft Exchange Server 스푸핑 취약성 Microsoft Office Access CVE-2021-41368 Microsoft Access 원격 코드 실행 취약성 Microsoft Office Excel CVE-2021-42292 Microsoft Excel 보안 기능 우회 취약성 Microsoft Office Excel CVE-2021-40442 Microsoft Excel 원격 코드 실행 취약성 Microsoft Office Word CVE-2021-42296 Microsoft Word 원격 코드 실행 취약성 Microsoft Windows CVE-2021-41356 Windows 암호화 서비스 거부 취약성 Microsoft Windows Codecs Library CVE-2021-42276 Windows 미디어 파운데이션 원격 코드 실행 취약성 Power BI CVE-2021-41372 Power BI Report Server Spoofing Vulnerability Role: Windows Hyper-V CVE-2021-42284 Windows Hyper-V 서비스 거부 취약성 Role: Windows Hyper-V CVE-2021-42274 Windows Hyper-V Discrete Device Assignment (DDA) Denial of Service Vulnerability Visual Studio CVE-2021-42319 Visual Studio 권한 상승 취약성 Visual Studio CVE-2021-3711 OpenSSL: CVE-2021-3711 SM2 Decryption Buffer Overflow Visual Studio Code CVE-2021-42322 Visual Studio Code 권한 상승 취약성 Windows Active Directory CVE-2021-42291 Active Directory Domain Services Elevation of Privilege Vulnerability Windows Active Directory CVE-2021-42287 Active Directory Domain Services Elevation of Privilege Vulnerability Windows Active Directory CVE-2021-42282 Active Directory Domain Services Elevation of

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.
Patch available
Affected
Fixed
An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
Action
Review the linked authoritative reference and apply the recorded fixed release appropriate to the affected product branch.
Workaround
No verified workaround is recorded. Limit untrusted access and use least privilege until authoritative guidance is available.
04

Evidence and provenance

Published 10 Nov 2021 · Last source change 19 Aug 2026, 16:27 UTC · CWE not yet assigned

CVE recordCVE.org · 5.2
CVSS sourceCNA
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-2021-29259
Product sourceCNA
Remediation sourceCVE/CNA references
CWE sourceUnavailable
NVD statusNVD modified after enrichment

Missing structured fields: CWE classification. Missing data is not evidence of low risk; review the primary advisory.

Material change intelligence

What changed after publication

View recent updates ↗
  1. Vendor guidanceAuthoritative vendor guidance changed: added remediation: portal.msrc.microsoft.com/CVE-2021-42284; removed patch: msrc.microsoft.com/CVE-2021-42284; removed remediation: msrc.microsoft.com/CVE-2021-42284.
    Before
    patch: msrc.microsoft.com/CVE-2021-42284 · patch: portal.msrc.microsoft.com/CVE-2021-42284 · remediation: msrc.microsoft.com/CVE-2021-42284
    After
    patch: portal.msrc.microsoft.com/CVE-2021-42284 · remediation: portal.msrc.microsoft.com/CVE-2021-42284
    portal.msrc.microsoft.com ↗
  2. Vendor guidanceAuthoritative vendor guidance changed: added patch: msrc.microsoft.com/CVE-2021-42284; added remediation: msrc.microsoft.com/CVE-2021-42284; removed remediation: portal.msrc.microsoft.com/CVE-2021-42284.
    Before
    patch: portal.msrc.microsoft.com/CVE-2021-42284 · remediation: portal.msrc.microsoft.com/CVE-2021-42284
    After
    patch: msrc.microsoft.com/CVE-2021-42284 · patch: portal.msrc.microsoft.com/CVE-2021-42284 · remediation: msrc.microsoft.com/CVE-2021-42284
    msrc.microsoft.com ↗
  3. Affected versionsThe structured affected or fixed version information changed.
    Before
    10.0.0 < 10.0.17763.2300; 10.0.0 < 10.0.18363.1916; 10.0.0 < 10.0.19043.1348; 10.0.0 < 10.0.20348.350; 10.0.0 < 10.0.19041.1348 · Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
    After
    10.0.10240.0 < 10.0.10240.19119; 10.0.14393.0 < 10.0.14393.4770; 10.0.17763.0 < 10.0.17763.2300; 10.0.0 < 10.0.18363.1916; 10.0.0 < 10.0.19041.1348; 10.0.0 < 10.0.19043.1348; 10.0.22000.0 < 10.0.22000.318; 6.3.0 < 6.3.9600.20174 · Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
    CNA ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Fixed release or patch reference recorded
ENISA EUVD · EUVD-2021-29259↗Patch or update reference↗CVE authority or vendor reference↗Official CVE record (CNA and ADP data)↗NVD record↗
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-2021-42284 · cve.blacktree.nl