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Vulnerabilities/CVE-2021-34527
Vulnerability dossier

CVE-2021-34527

VendormicrosoftPublishedJul 2, 2021SourceNVD
Act now

Actively exploited in the wild. Patch or mitigate immediately — don't wait for a maintenance window.

⚙ WeaponizedMetasploit module availableopen ↗
Severity
High · 8.8
CVSS base score
Exploitation
In the wild
CISA KEV · Metasploit
Predicted risk
100% model
EPSS forecast — overtaken by confirmed exploitation
Exposure
Remote (auth)
Remotely exploitable, but needs an account
01

What's the risk?

An attacker with a basic user account, remotely over the network, with no user interaction, can fully compromise the system — steal data, tamper with it and take it offline.

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.

How it's exploitedMITRE ATT&CK · inferred from weakness & vector
Initial Access
T1190
Exploit Public-Facing Application

Inferred from the weakness type (CWE) and how the flaw is reached — the techniques an attacker would chain to exploit this. Real-world corroboration appears here as threat intel is folded in.

02

Who's exploiting it?

Corroborated threat activity referencing this CVE — with source and confidence, not inference.

Confirmed exploited in the wild. CISA KEV · catalogued Nov 3, 2021
campaignRansomware campaigns90CISA KEV

Named threat actors and observed ATT&CK techniques appear here as intel feeds are folded in — the ATT&CK chain above stays inferred until then.

03

Are we affected?

17
  • Affectedmicrosoft · windows_10_1507< 10.0.10240.18969↑ fixed 10.0.10240.18969
  • Affectedmicrosoft · windows_10_1607< 10.0.14393.4470↑ fixed 10.0.14393.4470
  • Affectedmicrosoft · windows_10_1809< 10.0.17763.2029↑ fixed 10.0.17763.2029
  • Affectedmicrosoft · windows_10_20h2< 10.0.19042.1083↑ fixed 10.0.19042.1083
  • Affectedmicrosoft · windows_10_21h2< 10.0.19044.1415↑ fixed 10.0.19044.1415
  • Affectedmicrosoft · windows_10_22h2< 10.0.19045.2251↑ fixed 10.0.19045.2251
  • Affectedmicrosoft · windows_11_21h2< 10.0.22000.318↑ fixed 10.0.22000.318
  • Affectedmicrosoft · windows_11_22h2< 10.0.22621.674↑ fixed 10.0.22621.674
  • Affectedmicrosoft · windows_rt_8.1all versions
  • Affectedmicrosoft · windows_server_2008all versions
  • Affectedmicrosoft · windows_server_2008r2
  • Affectedmicrosoft · windows_server_2012all versions
  • Affectedmicrosoft · windows_server_2012r2
  • Affectedmicrosoft · windows_server_2016< 10.0.14393.4470↑ fixed 10.0.14393.4470
  • Affectedmicrosoft · windows_server_2019< 10.0.17763.2029↑ fixed 10.0.17763.2029
  • Affectedmicrosoft · windows_server_2022< 10.0.20348.230↑ fixed 10.0.20348.230
  • Affectedmicrosoft · windows_server_20h2< 10.0.19042.1083↑ fixed 10.0.19042.1083
04

What to do

Generated by Wavense from the CVE record — an immediate mitigation and the permanent fix.

  1. !

    Mitigate now

    Temporarily disable the Windows Print Spooler service on systems not requiring print functionality to eliminate the attack vector. If the service must run, restrict inbound remote printing and ensure that Point and Print registry settings 'NoWarningNoElevationOnInstall' and 'UpdatePromptSettings' are set to 0 or undefined. Implement network segmentation and monitor for suspicious activity originating from or targeting print services.

  2. ✓

    Permanent fix

    Apply the security updates released by Microsoft on July 6, 2021, and any subsequent cumulative updates immediately to all affected Windows systems. Refer to Microsoft's official advisories, such as KB5005010, for applicable updates and instructions. After patching, confirm that specific registry settings are correctly configured to restrict the installation of new printer drivers and secure the system.

Technical details— weakness, CVSS vector & calculator, related CVEs

Business impact

An attacker can exploit this vulnerability to execute arbitrary code with SYSTEM privileges on a compromised Windows system. This grants them full control, allowing them to install programs, view, alter, or delete data, and create new administrative accounts. The business consequences include severe data breaches, complete system compromise, and potential for widespread network infection.

Weakness

No CWE classification has been assigned.

CVSS 3.1 details

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
0.0
/ 10.0 base
High severity
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Exploitability metrics
Attack VectorAV
Remotely exploitable across a network
Attack ComplexityAC
No special conditions required
Privileges RequiredPR
Basic user privileges
User InteractionUI
No user participation needed
Impact metrics
ScopeS
Impact confined to the vulnerable component
ConfidentialityC
Total loss of confidentiality
IntegrityI
Total loss of integrity
AvailabilityA
Total loss of availability

Related vulnerabilities

Other CVEs affecting windows 10 1507

NVD
10.0Critical
CVE-2020-1350KEVExploit likely

A remote code execution vulnerability exists in Windows Domain Name System servers when they fail to properly handle requests, aka 'Windows DNS Server Remote Code Execution Vulnerability'.

microsoftCWE-20Improper Input ValidationNetworkLow effortNo authNo interactionCIA
2020-07-14
NVD
9.8Critical
CVE-2026-33824KEV

Double free in Windows IKE Extension allows an unauthorized attacker to execute code over a network.

microsoftCWE-415Double FreeNetworkLow effortNo authNo interactionCIA
2026-04-14
NVD
9.8Critical
CVE-2025-59287KEV⚙ WeaponizedExploit likely

Deserialization of untrusted data in Windows Server Update Service allows an unauthorized attacker to execute code over a network.

microsoftCWE-502Deserialization of Untrusted DataNetworkLow effortNo authNo interactionCIA
2025-10-14
NVD
9.8Critical
CVE-2021-31166KEV⚙ WeaponizedExploit likely

HTTP Protocol Stack Remote Code Execution Vulnerability

microsoftCWE-416Use After FreeNetworkLow effortNo authNo interactionCIA
2021-05-11
NVD
9.8Critical
CVE-2019-0708KEV⚙ WeaponizedExploit likely

A remote code execution vulnerability exists in Remote Desktop Services formerly known as Terminal Services when an unauthenticated attacker connects to the target system using RDP and sends specially crafted requests, aka 'Remote Desktop Services Remote Code Execution Vulnerability'.

huaweiCWE-416Use After FreeNetworkLow effortNo authNo interactionCIA
2019-05-16
NVD
9.8Critical
CVE-2017-8543KEVExploit likely

Microsoft Windows XP SP3, Windows XP x64 XP2, Windows Server 2003 SP2, Windows Vista, Windows 7 SP1, Windows Server 2008 SP2 and R2 SP1, Windows 8, Windows 8.1 and Windows RT 8.1, Windows Server 2012 and R2, Windows 10 Gold, 1511, 1607, and 1703, and Windows Server 2016 allow an attacker to take control of the affected system when Windows Search fails to handle objects in memory, aka "Windows Search Remote Code Execution Vulnerability".

microsoftCWE-281Improper Preservation of PermissionsNetworkLow effortNo authNo interactionCIA
2017-06-15
NVD
9.8Critical
CVE-2015-1635KEV⚙ WeaponizedExploit likely

HTTP.sys in Microsoft Windows 7 SP1, Windows Server 2008 R2 SP1, Windows 8, Windows 8.1, and Windows Server 2012 Gold and R2 allows remote attackers to execute arbitrary code via crafted HTTP requests, aka "HTTP.sys Remote Code Execution Vulnerability."

microsoftCWE-94Code InjectionNetworkLow effortNo authNo interactionCIA
2015-04-14
NVD
9.8Critical
CVE-2008-4250KEV⚙ WeaponizedExploit likely

The Server service in Microsoft Windows 2000 SP4, XP SP2 and SP3, Server 2003 SP1 and SP2, Vista Gold and SP1, Server 2008, and 7 Pre-Beta allows remote attackers to execute arbitrary code via a crafted RPC request that triggers the overflow during path canonicalization, as exploited in the wild by Gimmiv.A in October 2008, aka "Server Service Vulnerability."

microsoftCWE-94Code InjectionNetworkLow effortNo authNo interactionCIA
2008-10-23
0.0
/ 10.0 base
High severity
Key facts
CVE ID
CVE-2021-34527
Published
Jul 2, 2021
Last modified
Aug 10, 2026
CVSS
8.8 (v3.1)
EPSS
99.79%
In CISA KEV
Yes
Confidence
98/100
Fixed in
10.0.10240.18969, 10.0.14393.4470, 10.0.17763.2029…
Timeline
  1. Jul 2, 2021Published to NVDNVD
  2. Aug 10, 2026Record last modifiedNVD
  3. Jun 30, 2026AI analysis generatedWavense
View on NVD