Page generated: 08 Nov 2026, 13:35 UTC
CVE-2021-34527
PrintNightmare
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; …
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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.
CVSS 8.8 (HIGH) KEV: KNOWN CATALOG
Attention and evidence
HYPE SCORE
0.0/10
REALITY · THREAT PRIORITY
8.8/10
General review priority; not probability
Evidence confidence: Exploitation recorded
Sources: 32 documents and public datasets.
Hype components
Headline sample (25%)
0/100
Press, 30 days (60%)
0/100
Grounded branding (15%)
0/100
HYPE TOTAL0/100
Sources and documents
SentinelOne
Press · 27 Apr 2025, 07:00 · PrintNightmare Vulnerability: Analysis and Mitigation - SentinelOne
Dark Reading
Press · 29 Jan 2025, 08:00 · PrintNightmare Aftermath: Windows Print Spooler Is Better. What's Next? - Dark Reading
Microsoft
Press · 22 Apr 2024, 07:00 · Analyzing Forest Blizzard’s custom post-compromise tool for exploiting CVE-2022-38028 to obtain credentials - Microsoft
www.trendmicro.com
Press · 30 Jun 2022, 07:00 · Black Basta Ransomware Operators Expand Their Attack Arsenal With QakBot Trojan and PrintNightmare Exploit - www.trendmicro.com
Industrial Cyber
Press · 16 Mar 2022, 07:00 · US security agencies reveal that Russian hackers breach MFA, PrintNightmare vulnerability in NGO network - Industrial Cyber
Score evolution
● Hype ● Reality
Earlier evidence-support scores are retained in history; this chart shows only the current priority definition.
First record: hype 0.0 · reality 8.8 (2026-11-02 15:12). The curve appears once the score changes.
Public exploit evidence
4
Public exploit entries / repo candidates
Evidence context and dated references
Reality is general threat/review priority, combining observed exploitation, CVSS severity and fresh EPSS. Evidence confidence is separate. This is not calibrated risk, a victim count or an asset-specific assessment. A range reflects missing numeric inputs.
Evidence in context
- Confidence in exploitation evidence
- Exploitation recorded
- Priority basis
- Recorded exploitation; CVSS 8.8; EPSS 99.8%
- Attention, last 30 days
- 0 distinct story titles; 0 press documents; 0 publisher domains.
- Technical potential
- network access, low privileges, no user interaction.
- Observed activity
- Exploitation recorded in CISA KEV.
- Known scale
- Not quantified.
- Evidence confidence basis
- Trusted exploitation confirmation
Score evaluated: 2026-11-05 13:58:27.921902+00:00 · EPSS snapshot: 2026-11-05T12:03:04Z
Source event timeline
First press mention
30 Jun 2021, 07:00
Published
02 Jul 2021, 21:25
Added to the CISA KEV catalog
03 Nov 2021, 00:00
Latest press mention
27 Apr 2025, 07:00
Score calculated
05 Nov 2026, 13:58
Name
PrintNightmare
PoCs on GitHub
4 repositories