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Full vulnerability report · 2021
CVE-2021-34527High confidence

Microsoft Windows Print Spooler Remote Code Execution Vulnerability

Microsoft · Windows

8.8HighCVSS 3.1
Recommended action
Patch now

CISA confirms exploitation in the wild and lists 2022-05-03 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.
  • EPSS is 99.79% 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-2021-21181

CISA KEV mirrored by ENISA

A remote code execution vulnerability exists when the Windows Print Spooler service improperly performs privileged file operations. An attacker who successfully exploited this vulnerability could run arbitrary code with SYSTEM privileges. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. UPDATE July 7, 2021: The security update for Windows Server 2012, Windows Server 2016 and Windows 10, Version 1607 have been released. Please see the Security Updates table for the applicable update for your system. We recommend that you install these updates immediately. If you are unable to install these updates, see the FAQ and Workaround sections in this CVE for information on how to help protect your system from this vulnerability. In addition to installing the updates, in order to secure your system, you must confirm that the following registry settings are set to 0 (zero) or are not defined (Note: These registry keys do not exist by default, and therefore are already at the secure setting.), also that your Group Policy setting are correct (see FAQ): HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows NT\Printers\PointAndPrint NoWarningNoElevationOnInstall = 0 (DWORD) or not defined (default setting) UpdatePromptSettings = 0 (DWORD) or not defined (default setting) Having NoWarningNoElevationOnInstall set to 1 makes your system vulnerable by design. UPDATE July 6, 2021: Microsoft has completed the investigation and has released security updates to address this vulnerability. Please see the Security Updates table for the applicable update for your system. We recommend that you install these updates immediately. If you are unable to install these updates, see the FAQ and Workaround sections in this CVE for information on how to help protect your system from this vulnerability. See also KB5005010: Restricting installation of new printer drivers after applying the July 6, 2021 updates. Note that the security updates released on and after July 6, 2021 contain protections for CVE-2021-1675 and the additional remote code execution exploit in the Windows Print Spooler service known as “PrintNightmare”, documented in CVE-2021-34527.

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

CISA confirms exploitation in the wild and lists 2022-05-03 as the remediation due date.

Patch available
01

What, why and how

Microsoft Windows Print Spooler contains an unspecified vulnerability due to the Windows Print Spooler service improperly performing privileged file operations. Successful exploitation allows an attacker to perform remote code execution with SYSTEM privileges. The vulnerability is also known under the moniker of PrintNightmare.

What

Microsoft Windows Print Spooler contains an unspecified vulnerability due to the Windows Print Spooler service improperly performing privileged file operations. Successful exploitation allows an attacker to perform remote code execution with SYSTEM privileges. The vulnerability is also known under the moniker of PrintNightmare.

Why

The product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor.

How

An attacker operating through a network path may attempt exploitation with low privileges. If successful, the issue may execute code or commands in the affected security context.

What

Microsoft Windows Print Spooler contains an unspecified vulnerability due to the Windows Print Spooler service improperly performing privileged file operations. Successful exploitation allows an attacker to perform remote code execution with SYSTEM privileges. The vulnerability is also known under the moniker of PrintNightmare.

Why

The product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor.

How

An attacker operating through a network path may attempt exploitation with low privileges. If successful, the issue may execute code or commands in the affected security context.

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 → Improper Privilege Management → execute code or commands in the affected security context
Attack surface
Network
Privileges required
Low: a basic authenticated account 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-269 ↗

CWE-269: Improper Privilege Management. The product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor.

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:L/UI:N/S:U/C:H/I:H/A:H/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.PRLowPrivileges required: The attacker needs basic user-level 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.IHighIntegrity impact: A successful attack can cause a major loss.AHighAvailability impact: A successful attack can cause a major loss.
Post-exploitation / living off the land
After compromise, an attacker may use built-in shells, scripting engines, scheduled tasks and native network utilities for discovery, persistence or movement. This is a plausible LoTL path, not evidence that it has occurred for every attack.
NetworkRemote code executionCWE-269CISA 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-2021-21181Known-exploited evidence recorded

A remote code execution vulnerability exists when the Windows Print Spooler service improperly performs privileged file operations. An attacker who successfully exploited this vulnerability could run arbitrary code with SYSTEM privileges. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. UPDATE July 7, 2021: The security update for Windows Server 2012, Windows Server 2016 and Windows 10, Version 1607 have been released. Please see the Security Updates table for the applicable update for your system. We recommend that you install these updates immediately. If you are unable to install these updates, see the FAQ and Workaround sections in this CVE for information on how to help protect your system from this vulnerability. In addition to installing the updates, in order to secure your system, you must confirm that the following registry settings are set to 0 (zero) or are not defined (Note: These registry keys do not exist by default, and therefore are already at the secure setting.), also that your Group Policy setting are correct (see FAQ): HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows NT\Printers\PointAndPrint NoWarningNoElevationOnInstall = 0 (DWORD) or not defined (default setting) UpdatePromptSettings = 0 (DWORD) or not defined (default setting) Having NoWarningNoElevationOnInstall set to 1 makes your system vulnerable by design. UPDATE July 6, 2021: Microsoft has completed the investigation and has released security updates to address this vulnerability. Please see the Security Updates table for the applicable update for your system. We recommend that you install these updates immediately. If you are unable to install these updates, see the FAQ and Workaround sections in this CVE for information on how to help protect your system from this vulnerability. See also KB5005010: Restricting installation of new printer drivers after applying the July 6, 2021 updates. Note that the security updates released on and after July 6, 2021 contain protections for CVE-2021-1675 and the additional remote code execution exploit in the Windows Print Spooler service known as “PrintNightmare”, documented in CVE-2021-34527.

Official EUVD record ↗
Canadian Centre for Cyber Security · English · AL21-011Windows Print Spooler Vulnerability Remains Unpatched – update 3

On 29 June 2021, a proof-of-concept (POC) was released for an unpatched vulnerability in the Windows Print Spooler, colloquially named PrintNightmare.

Official advisory ↗
Cyber Security Agency of Singapore · English · CSA-SB-20210707Security Bulletin 07 Jul 2021

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 07 Jul 2021, published on 7 July 2021. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
CERT-FR · French · CERTFR-2022-AVI-215Multiples vulnérabilités dans les produits Schneider

d?id=CVE-2021-21829 Référence CVE CVE-2021-21830 https://www.cve.org/CVERecord?id=CVE-2021-21830 Référence CVE CVE-2021-22778 https://www.cve.org/CVERecord?id=CVE-2021-22778 Référence CVE CVE-2021-22779 https://www.cve.org/CVERecord?id=CVE-2021-22779 Référence CVE CVE-2021-22780 https://www.cve.org/CVERecord?id=CVE-2021-22780 Référence CVE CVE-2021-22781 https://www.cve.org/CVERecord?id=CVE-2021-22781 Référence CVE CVE-2021-22782 https://www.cve.org/CVERecord?id=CVE-2021-22782 Référence CVE CVE-2021-22783 https://www.cve.org/CVERecord?id=CVE-2021-22783 Référence CVE CVE-2021-22797 https://www.cve.org/CVERecord?id=CVE-2021-22797 Référence CVE CVE-2021-34527 https://www.cve.org/CVERecord?id=CVE-2021-34527 Référence CVE CVE-2022-0715 https://www.cve.org/CVERecord?id=CVE-2022-0715 Référence CVE CVE-2022-22805 https://www.cve.org/CVERecord?id=CVE-2022-22805 Référence CVE CVE-2022-22806 https://www.cve.org/CVERecord?id=CVE-2022-22806 Référence CVE CVE-2022-24322 https://www.cve.org/CVERecord?id=CVE-2022-24322 Référence CVE CVE-2022-24323 https://www.cve.org/CVERecord?id=CVE-2022-24323 Gestion détaillée du document le 08 mars 2022 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

Official advisory ↗
CERT-FR · French · CERTFR-2021-AVI-853Multiples vulnérabilités dans les produits Schneider

De multiples vulnérabilités ont été découvertes dans les produits Schneider. Certaines d'entre elles permettent à un attaquant de provoquer une exécution de code arbitraire à distance, un déni de service à distance et un contournement de la politique de sécurité.

Official advisory ↗
CERT-FR · French · CERTFR-2021-AVI-622Multiples vulnérabilités dans les produits Schneider Electric

d?id=CVE-2021-22789 Référence CVE CVE-2021-22790 https://www.cve.org/CVERecord?id=CVE-2021-22790 Référence CVE CVE-2021-22791 https://www.cve.org/CVERecord?id=CVE-2021-22791 Référence CVE CVE-2021-22792 https://www.cve.org/CVERecord?id=CVE-2021-22792 Référence CVE CVE-2021-22793 https://www.cve.org/CVERecord?id=CVE-2021-22793 Référence CVE CVE-2021-30186 https://www.cve.org/CVERecord?id=CVE-2021-30186 Référence CVE CVE-2021-30188 https://www.cve.org/CVERecord?id=CVE-2021-30188 Référence CVE CVE-2021-30195 https://www.cve.org/CVERecord?id=CVE-2021-30195 Référence CVE CVE-2021-31166 https://www.cve.org/CVERecord?id=CVE-2021-31166 Référence CVE CVE-2021-34527 https://www.cve.org/CVERecord?id=CVE-2021-34527 Gestion détaillée du document le 12 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 systèmes d'information

Official advisory ↗
CERT-FR · French · CERTFR-2021-AVI-506Vulnérabilité dans Microsoft Windows

Une vulnérabilité a été découverte dans Microsoft Windows. Elle permet à un attaquant de provoquer une exécution de code arbitraire à distance et une élévation de privilèges.

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2021-001967Microsoft Windows の印刷スプーラーにリモートコード実行の脆弱性

Microsoft Windows の Print Spooler サービスには、RpcAddPrinterDriverEx() 関数のアクセス制限の不備に起因するリモートコード実行の脆弱性が存在します。 Print Spooler サービスは、印刷において印刷待ちを実現するためのサービスです。RpcAddPrinterDriverEx() 関数は、上記サービスでプリンタドライバのインストールに用いられます。パラメータ DRIVER_CONTAINER オブジェクトとパラメータ dwFileCopyFlags によって、インストールするプリンタドライバとファイルのコピー方法を制御しています。 認証ユーザであれば、RpcAddPrinterDriverEx() 関数を実行可能です。そのため、認証情報を取得した攻撃者は、リモートサーバ上のドライバを指定し、インストールできます。

Official advisory ↗
KISA KrCERT/CC · Korean · KNVD-5951MS 7월 보안 위협에 따른 정기 보안 업데이트 권고

| Visual Studio | CVE-2023-21815 | Visual Studio 원격 코드 실행 취약성 | | .NET and Visual Studio | CVE-2023-21808 | .NET 및 Visual Studio 원격 코드 실행 취약성 | | Microsoft Graphics Component | CVE-2023-21756 | Windows Win32k 권한 상승 취약성 | | Azure DevOps | CVE-2023-21569 | Azure DevOps Server 스푸핑 취약성 | | Azure DevOps | CVE-2023-21565 | Azure DevOps Server 스푸핑 취약성 | | Windows Netlogon | CVE-2023-21526 | Windows Netlogon 정보 유출 취약성 | | .NET Framework | CVE-2022-41089 | .NET Framework 원격 코드 실행 취약성 | | Windows Netlogon | CVE-2022-38023 | Netlogon RPC 권한 상승 취약성 | | Windows Kerberos | CVE-2022-37967 | Windows Kerberos 권한 상승 취약성 | | Windows Print Spooler Components | CVE-2021-34527 | Windows 인쇄 스풀러 원격 코드 실행 취약성 | ##### □ 작성 : 취약점분석팀

Official advisory ↗
KISA KrCERT/CC · Korean · KNVD-5936MS 6월 보안 위협에 따른 정기 보안 업데이트 권고

-21738 | Microsoft Office Visio 원격 코드 실행 취약성 | | Azure DevOps | CVE-2023-21569 | Azure DevOps Server 스푸핑 취약성 | | Azure DevOps | CVE-2023-21565 | Azure DevOps Server 스푸핑 취약성 | | Microsoft Graphics Component | CVE-2022-41121 | Windows 그래픽 구성 요소 권한 상승 취약성 | | Microsoft Office Excel | CVE-2022-41104 | Microsoft Excel 보안 기능 우회 취약성 | | Windows Netlogon | CVE-2022-38023 | Netlogon RPC 권한 상승 취약성 | | Windows Kerberos | CVE-2022-37967 | Windows Kerberos 권한 상승 취약성 | | AMD CPU Branch | CVE-2022-29900 | AMD: CVE-2022-29900 AMD CPU 분기 유형 혼동 | | Windows Photo Import API | CVE-2022-26928 | Windows 사진 가져오기 API 권한 상승 취약성 | | Windows Print Spooler Components | CVE-2021-34527 | Windows 인쇄 스풀러 원격 코드 실행 취약성 | | Microsoft Office Outlook | CVE-2021-28452 | Microsoft Outlook 메모리 손상 취약성 | | WinVerifyTrust Signature Verification | CVE-2013-3900 | WinVerifyTrust 서명 유효 취약성 | ##### □ 작성 : 취약점분석팀

Official advisory ↗
KISA KrCERT/CC · Korean · KNVD-5322MS 윈도우 Print Spooler 취약점(CVE-2021-34527) 보안 업데이트 권고

Print Spooler에서 권한검증이 미흡하여 발생하는 원격코드실행 취약점(CVE-2021-34527) [1]

Official advisory ↗
KISA KrCERT/CC · Korean · KNVD-5319MS 윈도우즈 Print Spooler 취약점(CVE-2021-34527) 주의 권고

Print Spooler에서 권한검증이 미흡하여 발생하는 원격코드실행 취약점(CVE-2021-34527) [1]

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
A mitigation or workaround reference is available from the source linked below; validate it against the affected product and version.
04

Evidence and provenance

Published 2 Jul 2021 · Last source change 10 Aug 2026, 15:12 UTC · CWE-269 · Improper Privilege Management

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-2021-21181
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
    10.0.10240.0 < 10.0.10240.18969; 10.0.14393.0 < 10.0.14393.4470; 10.0.17763.0 < 10.0.17763.2029; 10.0.0 < 10.0.17763.2029; 10.0.0 < 10.0.19042.1083; 10.0.19044.0 < 10.0.19044.1415; 10.0.19045.0 < 10.0.19045.2251; 10.0.22000.0 < 10.0.22000.318 · 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 10 Version 1507: 10.0.10240.0 < 10.0.10240.18969; Windows 10 Version 1607: 10.0.14393.0 < 10.0.14393.4470; Windows 10 Version 1809: 10.0.17763.0 < 10.0.17763.2029, 10.0.0 < 10.0.17763.2029; Windows 10 Version 20H2: 10.0.0 < 10.0.19042.1083; Windows 10 Version 21H2: 10.0.19044.0 < 10.0.19044.1415; Windows 10 Version 22H2: 10.0.19045.0 < 10.0.19045.2251; Windows 11 version 21H2: 10.0.22000.0 < 10.0.22000.318; Windows 11 version 22H2: 10.0.22621.0 < 10.0.22621.674; Windows 8.1: 6.3.0 < 6.3.9600.20046; Windows Server 2008 R2 Service Pack 1: 6.1.7601.0 < 6.1.7601.25633; Windows Server 2008 R2 Service Pack 1 (Server Core installation): 6.1.7601.0 < 6.1.7601.25633; Windows Server 2008 Service Pack 2: 6.0.6003.0 < 6.0.6003.21138; Windows Server 2008 Service Pack 2 (Server Core installation): 6.0.6003.0 < 6.0.6003.21138; Windows Server 2012: 6.2.9200.0 < 6.2.9200.23383; Windows Server 2012 (Server Core installation): 6.2.9200.0 < 6.2.9200.23383; Windows Server 2012 R2: 6.3.9600.0 < 6.3.9600.20046; Windows Server 2012 R2 (Server Core installation): 6.3.9600.0 < 6.3.9600.20046; Windows Server 2016: 10.0.14393.0 < 10.0.14393.4470; Windows Server 2016 (Server Core installation): 10.0.14393.0 < 10.0.14393.4470; Windows Server 2019: 10.0.17763.0 < 10.0.17763.2029; Windows Server 2019 (Server Core installation): 10.0.17763.0 < 10.0.17763.2029; Windows Server 2022: 10.0.20348.0 < 10.0.20348.230; Windows Server version 20H2: 10.0.0 < 10.0.19042.1083 · 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-2021-21181↗CISA KEV record↗CVE authority or vendor reference↗Patch or update reference↗Public exploit 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-2021-34527 · cve.blacktree.nl