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Full vulnerability report · 2023
CVE-2023-21557High confidence

Windows Lightweight Directory Access Protocol (LDAP) Denial of Service Vulnerability

Microsoft · Windows 10 Version 1809

7.5HighCVSS 3.1
Recommended action
Within 7 days

High technical severity; prioritise exposed affected systems while verifying vendor guidance.

Fix not verified
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityHighOperational priority:High, unchanged from published severity.unchanged

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • The selected CVSS metric records a network-reachable, unauthenticated path with no user interaction.
  • EPSS is 2.03% for the current model date.

Compensating controls

  • Restrict the affected network interface to trusted sources where business-safe.
  • Monitor vendor guidance and exploitation sources for a material change.

Verification

  1. Confirm that the asset runs Microsoft Windows 10 Version 1809 and falls inside the recorded affected range.
  2. Recheck the vendor advisory before scheduling a change because no verified fixed version is currently retained.
  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 30 daysRemediation target: Within 180 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-2023-25724

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 actionWithin 7 days

High technical severity; prioritise exposed affected systems while verifying vendor guidance.

Fix not verified
01

What, why and how

Windows Lightweight Directory Access Protocol (LDAP) Denial of Service Vulnerability

What

Windows Lightweight Directory Access Protocol (LDAP) Denial of Service Vulnerability

Why

The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.

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

Windows Lightweight Directory Access Protocol (LDAP) Denial of Service Vulnerability

Why

The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.

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 → Integer Overflow or Wraparound → 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: a standard category for the underlying weakness.
CWE-190 ↗

CWE-190: Integer Overflow or Wraparound. The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.

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:N/I:N/A:H/E:U/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.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 serviceCWE-190
A

Official authority intelligence

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

BSI · German · WID-SEC-2023-0055Microsoft Windows und Microsoft Windows Server: Mehrere Schwachstellen

Ein Angreifer kann mehrere Schwachstellen in Microsoft Windows und Microsoft Windows Server ausnutzen, um beliebigen Code auszuführen, Sicherheitsmaßnahmen zu umgehen, vertrauliche Informationen offenzulegen, seine Privilegien zu erweitern und einen Denial-of-Service-Zustand auszulösen.

Official advisory ↗
Cyber Security Agency of Singapore · English · CSA-SB-20230111Security Bulletin 11 Jan 2023

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 11 Jan 2023, published on 11 January 2023. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
CERT-FR · French · CERTFR-2023-AVI-0022Multiples vulnérabilités dans Microsoft Windows

janvier 2023 https://msrc.microsoft.com/update-guide/vulnerability/CVE-2023-21550 Bulletin de sécurité Microsoft CVE-2023-21551 du 10 janvier 2023 https://msrc.microsoft.com/update-guide/vulnerability/CVE-2023-21551 Bulletin de sécurité Microsoft CVE-2023-21552 du 10 janvier 2023 https://msrc.microsoft.com/update-guide/vulnerability/CVE-2023-21552 Bulletin de sécurité Microsoft CVE-2023-21555 du 10 janvier 2023 https://msrc.microsoft.com/update-guide/vulnerability/CVE-2023-21555 Bulletin de sécurité Microsoft CVE-2023-21556 du 10 janvier 2023 https://msrc.microsoft.com/update-guide/vulnerability/CVE-2023-21556 Bulletin de sécurité Microsoft CVE-2023-21557 du 10 janvier 2023 https://msrc.microsoft.com/update-guide/vulnerability/CVE-2023-21557 Bulletin de sécurité Microsoft CVE-2023-21558 du 10 janvier 2023 https://msrc.microsoft.com/update-guide/vulnerability/CVE-2023-21558 Bulletin de sécurité Microsoft CVE-2023-21559 du 10 janvier 2023 https://msrc.microsoft.com/update-guide/vulnerability/CVE-2023-21559 Bulletin de sécurité Microsoft CVE-2023-21560 du 10 janvier 2023 https://msrc.microsoft.com/update-guide/vulnerability/CVE-2023-21560 Bulletin de sécurité Microsoft CVE-2023-21561 du 10 janvier 2023 https://msrc.microsoft.com/update-guide/vulnerability/CVE-2023-21561 Bulletin de sécurité Micr

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2023-001022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 ライトウェイトディレクトリアクセスプロトコル (LDAP) 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-5823MS 1월 보안 위협에 따른 정기 보안 업데이트 권고

ightweight Directory Access Protocol CVE-2023-21676 Windows LDAP(Lightweight Directory Access Protocol) 원격 코드 실행 취약점 Windows Virtual Registry Provider CVE-2023-21675 Windows 커널 권한 상승 취약점 Windows ALPC CVE-2023-21674 Windows 고급 로컬 프로시저 호출(ALPC) 권한 상승 취약점 Windows BitLocker CVE-2023-21563 BitLocker 보안 기능 우회 취약점 Windows Cryptographic Services CVE-2023-21561 Microsoft Cryptographic Services 권한 상승 취약점 Windows Boot Manager CVE-2023-21560 Windows 부팅 관리자 보안 기능 우회 취약점 Windows Cryptographic Services CVE-2023-21559 Windows 암호화 정보 공개 취약점 Windows Error Reporting CVE-2023-21558 Windows 오류 보고 서비스 권한 상승 취약점 Windows LDAP - Lightweight Directory Access Protocol CVE-2023-21557 Windows LDAP(Lightweight Directory Access Protocol) 서비스 거부 취약점 Windows Layer 2 Tunneling Protocol CVE-2023-21556 Windows 레이어 2 터널링 프로토콜(L2TP) 원격 코드 실행 취약점 Windows Layer 2 Tunneling Protocol CVE-2023-21555 Windows 레이어 2 터널링 프로토콜(L2TP) 원격 코드 실행 취약점 Microsoft Graphics Component CVE-2023-21552 Windows GDI 권한 상승 취약점 Windows Cryptographic Services CVE-2023-21551 Microsoft Cryptographic Services 권한 상승 취약점 Windows Cryptographic Services CVE-2023-21550 Windows 암호화 정보 공개 취약점 Windows Workstation Service CVE-2023-21549 Windows SMB 감시 서비스 권한 상승 취약점 Windows Secure Socket Tunneling Protocol (SSTP) CVE-2023-21548 Windows SSTP(Secure Socket Tunneling Protoco

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
  • Windows 10 Version 1809: 10.0.17763.0 < 10.0.17763.3887, 10.0.0 < 10.0.17763.3887
  • Windows Server 2019: 10.0.17763.0 < 10.0.17763.3887
  • Windows Server 2019 (Server Core installation): 10.0.17763.0 < 10.0.17763.3887
  • Windows Server 2022: 10.0.20348.0 < 10.0.20348.1487
  • Windows 10 Version 20H2: 10.0.0 < 10.0.19042.2486
  • Windows 11 version 21H2: 10.0.0 < 10.0.22000.1455
  • Windows 10 Version 21H2: 10.0.19043.0 < 10.0.19044.2486
  • Windows 11 version 22H2: 10.0.22621.0 < 10.0.22621.1105
  • Windows 10 Version 22H2: 10.0.19045.0 < 10.0.19045.2486
  • Windows 10 Version 1507: 10.0.10240.0 < 10.0.10240.19685
  • Windows 10 Version 1607: 10.0.14393.0 < 10.0.14393.5648
  • Windows Server 2016: 10.0.14393.0 < 10.0.14393.5648
  • Windows Server 2016 (Server Core installation): 10.0.14393.0 < 10.0.14393.5648
  • Windows 7: 6.1.0 < 6.1.7601.26321
  • Windows 7 Service Pack 1: 6.1.0 < 6.1.7601.26321
  • Windows 8.1: 6.3.0 < 6.3.9600.20778
  • Windows Server 2008 Service Pack 2: 6.0.6003.0 < 6.0.6003.21872
  • Windows Server 2008 Service Pack 2 (Server Core installation): 6.0.6003.0 < 6.0.6003.21872
  • Windows Server 2008 Service Pack 2: 6.0.6003.0 < 6.0.6003.21872
  • Windows Server 2008 R2 Service Pack 1: 6.1.7601.0 < 6.1.7601.26321
  • Windows Server 2008 R2 Service Pack 1 (Server Core installation): 6.1.7601.0 < 6.1.7601.26321
  • Windows Server 2012: 6.2.9200.0 < 6.2.9200.24075
  • Windows Server 2012 (Server Core installation): 6.2.9200.0 < 6.2.9200.24075
  • Windows Server 2012 R2: 6.3.9600.0 < 6.3.9600.20778
  • Windows Server 2012 R2 (Server Core installation): 6.3.9600.0 < 6.3.9600.20778
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. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04

Evidence and provenance

Published 10 Jan 2023 · Last source change 1 Jan 2025, 00:35 UTC · CWE-190 · Integer Overflow or Wraparound

CVE recordCVE.org · 5.1
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-2023-25724
Product sourceCNA
Remediation sourceCVE/CNA references
CWE sourceOther authority
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-2023-21557 · cve.blacktree.nl