High technical severity; prioritise exposed affected systems while verifying vendor guidance.
Patch available
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-2020-2377
No EUVD known-exploited evidence
A denial of service vulnerability exists when Hyper-V on a Windows Server fails to properly handle specially crafted network packets.
To exploit the vulnerability, an attacker would send specially crafted network packets to the Hyper-V Server.
The security update addresses the vulnerability by resolving the conditions where Hyper-V would fail to properly handle these network packets.
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
7.5 · CVSS 3.1
Advisory evidence
No linked advisory details stored yet
Recommended actionWithin 7 days
High technical severity; prioritise exposed affected systems while verifying vendor guidance.
Patch available
01
What, why and how
A denial of service vulnerability exists when Hyper-V on a Windows Server fails to properly handle specially crafted network packets.
To exploit the vulnerability, an attacker would send specially crafted network packets to the Hyper-V Server.
The security update addresses the vulnerability by resolving the conditions where Hyper-V would fail to properly handle these network packets.
What
A denial of service vulnerability exists when Hyper-V on a Windows Server fails to properly handle specially crafted network packets.
To exploit the vulnerability, an attacker would send specially crafted network packets to the Hyper-V Server.
The security update addresses the vulnerability by resolving the conditions where Hyper-V would fail to properly handle these network packets.
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 a network path may attempt exploitation without authentication or user interaction. If successful, the issue may disrupt the affected service.
What
A denial of service vulnerability exists when Hyper-V on a Windows Server fails to properly handle specially crafted network packets.
To exploit the vulnerability, an attacker would send specially crafted network packets to the Hyper-V Server.
The security update addresses the vulnerability by resolving the conditions where Hyper-V would fail to properly handle these network packets.
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 a network path may attempt exploitation without authentication or user interaction. 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
a network path → vulnerable operation → disrupt the affected service
Attack surface
Network
Privileges required
None: unauthenticated exploitation is possible
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.
CWE not yet assigned
CVSS vector ?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
Common Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.
AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRNonePrivileges required: The attacker does not need an account or existing 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
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.
NetworkUnauthenticatedDenial of service
A
Official authority intelligence
Only matched European and national findings are included. Language selectors and unavailable sources are omitted.
ENISA EUVD · EUVD-2020-2377Official EUVD mapping
A denial of service vulnerability exists when Hyper-V on a Windows Server fails to properly handle specially crafted network packets.
To exploit the vulnerability, an attacker would send specially crafted network packets to the Hyper-V Server.
The security update addresses the vulnerability by resolving the conditions where Hyper-V would fail to properly handle these network packets.
Official EUVD record ↗CERT-FR · French · CERTFR-2020-AVI-287Multiples vulnérabilités dans Microsoft Windows
tallation)
Windows Server, version 1909 (Server Core installation)
Résumé
De multiples vulnérabilités ont été corrigées dans Microsoft Windows . Elles permettent à un attaquant
de provoquer une élévation de privilèges, une usurpation d'identité, une
exécution de code à distance, un déni de service, un contournement de la
fonctionnalité de sécurité et une atteinte à la confidentialité des
données.
Solution
Se référer au bulletin de sécurité de l'éditeur pour l'obtention des
correctifs (cf. section Documentation).
Documentation
Bulletin de sécurité Microsoft du 12 mai 2020
https://portal.msrc.microsoft.com/fr-FR/security-guidance
Référence CVE CVE-2020-0909
https://www.cve.org/CVERecord?id=CVE-2020-0909
Référence CVE CVE-2020-0963
https://www.cve.org/CVERecord?id=CVE-2020-0963
Référence CVE CVE-2020-1010
https://www.cve.org/CVERecord?id=CVE-2020-1010
Référence CVE CVE-2020-1021
https://www.cve.org/CVERecord?id=CVE-2020-1021
Référence CVE CVE-2020-1028
https://www.cve.org/CVERecord?id=CVE-2020-1028
Référence CVE CVE-2020-1048
https://www.cve.org/CVERecord?id=CVE-2020-1048
Référence CVE CVE-2020-1051
https://www.cve.org/CVERecord?id=CVE-2020-1051
Référence CVE CVE-2020-1054
https://www.cve.org/CVERecord?id=CVE-2020-1054
Référence CVE CVE-2020-1055
https://www.cve.org/CVERecord?id=CVE-2020-1055
Ré
Official advisory ↗JVN iPedia · Japanese · JVNDB-2020-005822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 Server 上の Hyper-V が巧妙に細工されたネットワークパケットの適切な処理に失敗した場合、権限を昇格される脆弱性が存在します。 ベンダは、本脆弱性を「Windows Hyper-V のサービス拒否の脆弱性」として公開しています。
Official advisory ↗KISA KrCERT/CC · Korean · KNVD-5139MS 5월 보안 위협에 따른 정기 보안 업데이트 권고
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.
Review the linked authoritative reference and apply the recorded fixed release appropriate to the affected product branch.
Workaround
No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04
Evidence and provenance
Published 21 May 2020 · Last source change 19 Aug 2026, 16:33 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-2020-2377
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.
Affected versionsThe structured affected or fixed version information changed.
Before
10 Version 1803 for x64-based Systems; 10 Version 1809 for x64-based Systems; 10 Version 1709 for x64-based Systems; 10 for x64-based Systems; 10 Version 1607 for x64-based Systems; 7 for x64-based Systems Service Pack 1; 8.1 for x64-based systems; version 1803 (Core Installation) · 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 < publication; 10.0.14393.0 < publication; 10.0.0 < publication; 10.0.17763.0 < publication; 6.1.0 < publication · 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.
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.
CVE-2020-0909: Windows Hyper-V Denial of Service Vulnerability | BlackTree
