CVE-2021-34527
Exploited in the Wild
✓ Confirmed 0-Day
Triaged: March 5, 2026
19 articles
EPSS Score
Source: FIRST.org · 2026-05-24
94.24%
probability
This CVE has a 94.24% probability
of being exploited in the next 30 days.
0%
Top 99.9th percentile of all CVEs
100%
CVSS v3.1
Source: NVD8.8
HIGH
Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CVSS v2 (legacy)
9.0
HIGH
Access Vector
Network
Access Complexity
Low
Authentication
Single
Confidentiality
Complete
Integrity
Complete
Availability
Complete
AV:N/AC:L/Au:S/C:C/I:C/A:C
Description
NVD<p>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.</p>
<p>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.</p>
<p>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 (<strong>Note</strong>: 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):</p>
<ul>
<li>HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows NT\Printers\PointAndPrint</li>
<li>NoWarningNoElevationOnInstall = 0 (DWORD) or not defined (default setting)</li>
<li>UpdatePromptSettings = 0 (DWORD) or not defined (default setting)</li>
</ul>
<p><strong>Having NoWarningNoElevationOnInstall set to 1 makes your system vulnerable by design.</strong></p>
<p>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 <a href="https://support.microsoft.com/topic/31b91c02-05bc-4ada-a7ea-183b129578a7">KB5005010: Restricting installation of new printer drivers after applying the July 6, 2021 updates</a>.</p>
<p>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.</p>
Affected Products
microsoft
windows 10 1507
microsoft
windows 10 1607
microsoft
windows 10 1809
microsoft
windows 10 20h2
microsoft
windows 10 21h2
Exploits & PoC
JohnHammond/CVE-2021-34527
PoC CVE-2021-34527 — JohnHammond/CVE-2021-34527
315
nemo-wq/PrintNightmare-CVE-2021-34527
PrintNightmare - Windows Print Spooler RCE/LPE Vulnerability (CVE-2021-34527, CVE-2021-1675) proof of concept exploits
171
m8sec/CVE-2021-34527
PrintNightmare (CVE-2021-34527) PoC Exploit
120
dywhoami/CVE-2021-34527-Scanner-Based-On-cube0x0-POC
PoC CVE-2021-34527 — dywhoami/CVE-2021-34527-Scanner-Based-On-cube0x0-POC
3
Tomparte/PrintNightmare
To fight against Windows security breach PrintNightmare! (CVE-2021-34527, CVE-2021-1675)
3
thomas-lauer/PrintNightmare
Kritische Sicherheitslücke PrintNightmare CVE-2021-34527
2
6 repos — triés par ⭐
Rechercher sur GitHub ↗
http://packetstormsecurity.com/files/167261/Print-Spooler-Remote-DLL-Injection.html
Exploit
Third Party Advisory
VDB Entry
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-34527
Mitigation
Patch
Vendor Advisory
http://packetstormsecurity.com/files/167261/Print-Spooler-Remote-DLL-Injection.html
Exploit
Third Party Advisory
VDB Entry
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-34527
Mitigation
Patch
Vendor Advisory
https://www.kb.cert.org/vuls/id/383432
Third Party Advisory
US Government Resource
https://www.vicarius.io/vsociety/posts/cve-2021-34527-printnightmare-detection-script
Exploit
Third Party Advisory
https://www.vicarius.io/vsociety/posts/cve-2021-34527-printnightmare-mitigation-script
Exploit
Third Party Advisory
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-34527
US Government Resource
Signal Intelligence
Confidence
85%
EPSS
94.24%
CVSS v3.1
8.8
Mentions
19
Last Seen
Sep 19, 2024
CNA Information
Analyst Note
CVE-2021-34527 is the PrintNightmare RCE vulnerability. Multiple authoritative sources document active exploitation in the wild immediately following disclosure in early July 2021, before Microsoft's patch became widely available on Patch Tuesday (July 13, 2021). The gap between CVE publication (July 2) and exploitation reports was minimal, consistent with zero-day activity.
Threat Actors 14
Lazarus Group
apt_group
Information theft and espionage
🇰🇵 KP
Turla Group
apt_group
Information theft and espionage
Russian Federation
APT 29
apt_group
Information theft and espionage
🇷🇺 RU
WIZARD SPIDER
apt_group
Financial gain
🇷🇺 RU
Cobalt
apt_group
Financial crime
🇷🇺 RU
FIN7
apt_group
Financial crime
🇷🇺 RU
APT32
apt_group
Information theft and espionage
🇻🇳 VN
Kimsuky
apt_group
Information theft and espionage
🇰🇷 KR
MageCart
apt_group
Financial gain
🇷🇺 RU
Hacking Team
apt_group
🇮🇹 IT
Bitwise Spider
apt_group
Financial gain
🇷🇺 RU
WildPressure
apt_group
Information theft and espionage
UNKNOWN
Shadow Network
apt_group
Information theft and espionage
🇨🇳 CN
APT 5
apt_group
Information theft and espionage
🇨🇳 CN
Triage Info
Decided atMar 05, 2026