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Full vulnerability report · 2021
CVE-2021-36942High confidence

Microsoft Windows Local Security Authority (LSA) Spoofing Vulnerability

Microsoft · Windows

7.5HighCVSS 3.1
Recommended action
Patch now

CISA confirms exploitation in the wild and lists 2021-11-17 as the remediation due date.

Patch available
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityHighOperational priority:Critical, raised one band.upgradedsince 3 Nov 2021

Evidence used

  • CISA confirms exploitation in the wild.
  • A structured source references public exploit or proof-of-concept material.
  • The selected CVSS metric records a network-reachable, unauthenticated path with no user interaction.
  • EPSS is 66.02% for the current model date.

Compensating controls

  • Validate the affected product branch and deploy the verified fixed release.
  • Restrict the affected network interface to trusted sources where business-safe.
  • Increase monitoring for the attack path and post-exploitation behaviour described in the report.

Verification

  1. Confirm that the asset runs Microsoft Windows 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: Within 3 daysRemediation target: Within 90 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-2021-23518

CISA KEV mirrored by ENISA

Windows LSA Spoofing Vulnerability

EUVD state
Present in the current official mapping
Known exploitation
Recorded by ENISA since 3 Nov 2021. Evidence sources: cisa_kev.
ENISA score
7.5 · CVSS 3.1
Advisory evidence
No linked advisory details stored yet
Recommended actionPatch now

CISA confirms exploitation in the wild and lists 2021-11-17 as the remediation due date.

Patch available
01

What, why and how

Microsoft Windows Local Security Authority (LSA) contains a spoofing vulnerability allowing an unauthenticated attacker to call a method on the LSARPC interface and coerce the domain controller to authenticate against another server using NTLM.

What

Microsoft Windows Local Security Authority (LSA) contains a spoofing vulnerability allowing an unauthenticated attacker to call a method on the LSARPC interface and coerce the domain controller to authenticate against another server using NTLM.

Why

The product provides an Applications Programming Interface (API) or similar interface for interaction with external actors, but the interface includes a dangerous method or function that is not properly restricted.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

What

Microsoft Windows Local Security Authority (LSA) contains a spoofing vulnerability allowing an unauthenticated attacker to call a method on the LSARPC interface and coerce the domain controller to authenticate against another server using NTLM.

Why

The product provides an Applications Programming Interface (API) or similar interface for interaction with external actors, but the interface includes a dangerous method or function that is not properly restricted.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

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.
Confirmed in the wild

CISA added this CVE to its Known Exploited Vulnerabilities catalogue on 2021-11-03. Known ransomware campaign use is recorded.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
Reference recorded

A structured CVE source labels at least one public reference as exploit material. BlackTree has not independently validated that it is safe, reliable or weaponised.

Likely attack path
a network path → Exposed Dangerous Method or Function → cause the confidentiality, integrity or availability impact described by the vendor
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: a standard category for the underlying weakness.
CWE-749 ↗

CWE-749: Exposed Dangerous Method or Function. The product provides an Applications Programming Interface (API) or similar interface for interaction with external actors, but the interface includes a dangerous method or function that is not properly restricted.

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

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.CHighConfidentiality impact: A successful attack can cause a major loss.INoneIntegrity impact: No direct loss is represented by this metric.ANoneAvailability impact: No direct loss is represented by this metric.
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.
NetworkUnauthenticatedCWE-749CISA KEVPublic exploit reference
A

Official authority intelligence

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

ENISA EUVD · EUVD-2021-23518Known-exploited evidence recorded

Windows LSA Spoofing Vulnerability

Official EUVD record ↗
Cyber Security Agency of Singapore · English · CSA-SB-20210818Security Bulletin 18 Aug 2021

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 18 Aug 2021, published on 18 August 2021. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
CERT-FR · French · CERTFR-2021-AVI-618Multiples vulnérabilités dans Microsoft Windows

d?id=CVE-2021-34536 Référence CVE CVE-2021-34537 https://www.cve.org/CVERecord?id=CVE-2021-34537 Référence CVE CVE-2021-36926 https://www.cve.org/CVERecord?id=CVE-2021-36926 Référence CVE CVE-2021-36927 https://www.cve.org/CVERecord?id=CVE-2021-36927 Référence CVE CVE-2021-36932 https://www.cve.org/CVERecord?id=CVE-2021-36932 Référence CVE CVE-2021-36933 https://www.cve.org/CVERecord?id=CVE-2021-36933 Référence CVE CVE-2021-36936 https://www.cve.org/CVERecord?id=CVE-2021-36936 Référence CVE CVE-2021-36937 https://www.cve.org/CVERecord?id=CVE-2021-36937 Référence CVE CVE-2021-36938 https://www.cve.org/CVERecord?id=CVE-2021-36938 Référence CVE CVE-2021-36942 https://www.cve.org/CVERecord?id=CVE-2021-36942 Référence CVE CVE-2021-36945 https://www.cve.org/CVERecord?id=CVE-2021-36945 Référence CVE CVE-2021-36947 https://www.cve.org/CVERecord?id=CVE-2021-36947 Référence CVE CVE-2021-36948 https://www.cve.org/CVERecord?id=CVE-2021-36948 Gestion détaillée du document le 11 août 2021 Version initiale Alertes Avis Bulletins d’actualités Mentions légales Conditions générales À propos Contact cyber.gouv.fr service-public.fr legifrance.gouv.fr info.gouv.fr france.fr info.gouv.fr/risques Premier Ministre / Secrétariat Général de la Défense et de la Sécurité Nationale / Agence nationale de la sécurité des sy

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2021-002297Microsoft Windows Server におけるなりすまされる脆弱性

Microsoft Windows Server には、Windows LSA に不備があるため、なりすまされる脆弱性が存在します。

Official advisory ↗
KISA KrCERT/CC · Korean · KNVD-5362MS 8월 보안 위협에 따른 정기 보안 업데이트 권고

원격 코드 실행 취약성 Remote Desktop Connection Manager CVE-2020-0765 원격 데스크톱 연결 관리자 정보 유출 취약성 Windows Bluetooth Service CVE-2021-34537 Windows Bluetooth 드라이버 권한 상승 취약성 Windows Cryptographic Services CVE-2021-36938 Windows 암호화 기본 형식 라이브러리 정보 공개 취약성 Windows Defender CVE-2021-34471 Microsoft Windows Defender 권한 상승 취약성 Windows Event Tracing CVE-2021-34487 Windows 이벤트 추적 권한 상승 취약성 Windows Event Tracing CVE-2021-34486 Windows 이벤트 추적 권한 상승 취약성 Windows Event Tracing CVE-2021-26425 Windows 이벤트 추적 권한 상승 취약성 Windows Media CVE-2021-36927 Windows 디지털 TV 튜너 장치 등록 응용 프로그램 권한 상승 취약성 Windows MSHTML Platform CVE-2021-34534 Windows MSHTML 플랫폼 원격 코드 실행 취약성 Windows NTLM CVE-2021-36942 Windows LSA 스푸핑 취약성 Windows Print Spooler Components CVE-2021-36947 Windows 인쇄 스풀러 원격 코드 실행 취약성 Windows Print Spooler Components CVE-2021-36936 Windows 인쇄 스풀러 원격 코드 실행 취약성 Windows Print Spooler Components CVE-2021-34483 Windows 인쇄 스풀러 권한 상승 취약성 Windows Print Spooler Components CVE-2021-34481 Windows 인쇄 스풀러 원격 코드 실행 취약성 Windows Services for NFS ONCRPC XDR Driver CVE-2021-36933 NFS ONCRPC XDR 드라이버용 Windows 서비스 정보 공개 취약성 Windows Services for NFS ONCRPC XDR Driver CVE-2021-36932 NFS ONCRPC XDR 드라이버용 Windows 서비스 정보 공개 취약성 Windows Services for NFS ONCRPC XDR Driver CVE-2021-36926 NFS ONCRPC XDR 드라이버용 Windows 서비스 정보 공개 취약성 Windows Services for NFS

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. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04

Evidence and provenance

Published 12 Aug 2021 · Last source change 10 Aug 2026, 15:10 UTC · CWE-749 · Exposed Dangerous Method or Function

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-2021-23518
Product sourceCISA KEV
Remediation sourceCVE/CNA references
CWE sourceCISA KEV
NVD statusNVD enriched

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

Material change intelligence

What changed after publication

View recent updates ↗
  1. Affected versionsThe structured affected or fixed version information changed.
    Before
    6.1.7601.0 < 6.1.7601.25685; 6.0.6003.0 < 6.0.6003.21192; 6.2.9200.0 < 6.2.9200.23435; 6.3.9600.0 < 6.3.9600.20094 · 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
    Windows Server 2008 R2 Service Pack 1: 6.1.7601.0 < 6.1.7601.25685; Windows Server 2008 R2 Service Pack 1 (Server Core installation): 6.1.7601.0 < 6.1.7601.25685; Windows Server 2008 Service Pack 2: 6.0.6003.0 < 6.0.6003.21192; Windows Server 2008 Service Pack 2 (Server Core installation): 6.0.6003.0 < 6.0.6003.21192; Windows Server 2012: 6.2.9200.0 < 6.2.9200.23435; Windows Server 2012 (Server Core installation): 6.2.9200.0 < 6.2.9200.23435; Windows Server 2012 R2: 6.3.9600.0 < 6.3.9600.20094; Windows Server 2012 R2 (Server Core installation): 6.3.9600.0 < 6.3.9600.20094; Windows Server 2016: 10.0.14393.0 < 10.0.14393.4583; Windows Server 2016 (Server Core installation): 10.0.14393.0 < 10.0.14393.4583; Windows Server 2019: 10.0.17763.0 < 10.0.17763.2114; Windows Server 2019 (Server Core installation): 10.0.17763.0 < 10.0.17763.2114; Windows Server version 2004: 10.0.0 < 10.0.19041.1165; Windows Server version 20H2: 10.0.0 < 10.0.19042.1165 · 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
Added to CISA KEV
Fixed release or patch reference recorded
ENISA EUVD · EUVD-2021-23518↗CISA KEV record↗CVE authority or vendor reference↗Patch or update reference↗Public exploit 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-2021-36942 · cve.blacktree.nl