CVE-2021-34527 · PrintNightmare
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Windows Print Spooler Remote Code Execution Vulnerability
rank 78 = 40 + 23 + 0 + 9 + 6
rank@v1 · act now
Someone is already using it
CISA KEV catalog · public proof-of-concept · FIRST EPSS
EPSS 0.99792 · CISA KEV listed · without this subject the record ranks 38
What it costs you if it fires
NVD CVSS base score, then the CNA's own
CVSS 9.0, from NVD · without this subject the record ranks 55
It is getting worse, not staying still
FIRST EPSS series, rescorings and bad loads removed
no persisting rise in 365 days · without this subject the record ranks 78
How much of the world it touches
NVD CPE configurations
14 products in the CPE ranges · without this subject the record ranks 69
Someone else already set the date
CISA KEV remediation due date
CISA remediation date held · without this subject the record ranks 72
$4.98M = $4.99M incident cost x 1 exposure x 0.99792 likelihood
udv@v1 · unaudited · wrong for you until you say what you run
$4.99M is the cost of a breach that happened, from IBM Cost of a Data Breach Report 2026, global average. It is not the value of any asset of yours. That average already covers breaches of every severity, so scaling it by exposure understates a partial-impact record. That is an assumption, not a measurement. Your own asset value goes in the decision record.
Hindsight · the state
Foresight · where to check next
No weakness class or product neighbourhood is held for this record, so this index cannot name anywhere to check next. That is an absence in the record, not a finding about the software.
Sources disagree here.
Both shown, dated. We don't pick winners. disagreement-rules@v1
Running Microsoft Windows 10 Version 1507? Check your version
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Harm, if it fires from the vector and the weakness
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CISA KEV & Federal Remediation Deadline from the record and CISA
The fix, and how long it's been waiting.
Exploit Status & Known PoCs a ladder, not a score
Current rung: Ransomware campaign use known, 2021-11-03.
Affected & Fixed Versions as published
Show all 14 published ranges
A rung lights from a row in the index, never from an assessment. "Held sources" is the true scope of the claim: this index reads the CVE record, NVD, CISA KEV, FIRST's EPSS and public proof-of-concept repositories, and it does not observe attacks.
What it is stated by the CNA
PrintNightmare is the common name for CVE-2021-34527. 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. cve-aliases@2026-08-27
Read the rest of the CNA's description
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.
NVD's analysis a second authority
- severity
- 9 AV:N/AC:L/Au:S/C:C/I:C/A:C
- affected versions
- microsoft windows 10 1507 < 10.0.10240.18969; microsoft windows 10 1607 < 10.0.14393.4470; microsoft windows 10 1809 < 10.0.17763.2029; and 11 more, listed in full below
- also scored by
- [email protected] 8.8 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H · [email protected] 8.8 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
The CNA scored it 8.8 and NVD 9. Both are shown because both were published; we do not pick one.
check it yourself msrc.microsoft.com receipt
Dated events
Movement the material steps
This score more than doubled inside 72 hours. Both observations are in the full history below.
Show all 63 observations
63 observations held. A highlighted step crossed a promotion threshold. A step marked with a scoring model moved because the instrument was replaced, not because the vulnerability changed. receipt
The full biography
Listed by CISA 124 days after it published, exploit probability more than doubled between 2022-01-05 and 2022-01-06 (0.32208 → 0.7783) and the record had been public for 5 years, 2 months when this index was last written.
No material movement in 24 days as of the last ingest this index recorded.
Siblings and hubs
Records related to this one
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These are index-wide views, not findings about CVE-2021-34527.
What usually comes next
Everything above needs no account. What is below is work: assembling it, scoping it to your estate, watching it, and handing it to someone else.