CVE-2021-34527

HIGHNVD 8.89.0▲
EchelonGraph scoreHIGH confidence

Score elevated to 9.0 because this CVE is listed on the CISA Known Exploited Vulnerabilities catalog (added 2021-11-03), indicating real-world exploitation has been confirmed by US federal agencies. NVD baseline CVSS 8.8 retained for reference. Confidence: HIGH.

Triggered by: CISA KEV (actively exploited)
Sources: cisa_kev, epss, ghsa, nvd
Trending — 5 sources updated this weekExploited in the wild
8.8
EchelonGraph verdictPatch nowTreat as an emergency — this is being exploited.
  • Actively exploited in the wild (CISA-KEV)
CISA-KEV: ExploitedEPSS: 100%CVSS: 8.8Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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 v3
8.8
EG Score
9.0(high)
EG Risk
81(Attend)
EG Risk 81/100SSVC: Attend

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity90% × 45%
Exploitation100% × 40%
Automatability0% × 15%
Action: Remediate soon — notable exploitation risk.
EPSS
100.0%
KEV
⚠ Exploited

Published

July 2, 2021

Last Modified

June 17, 2026

Advisory Details (6)

Auto-updated Jun 2, 2026
⚠️ Active exploitation confirmed. Patch available. Sources: microsoft, cert, cisa.
cisa Patch Available🔴 Active Exploitation

Known Exploited Vulnerabilities Catalog | CISA

Known Exploited Vulnerabilities Catalog | CISA. Listed in CISA Known Exploited Vulnerabilities catalog.

https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-34527
generic

CVE-2021-34527 - PrintNightmare - Mitigation Script - vsociety

https://www.vicarius.io/vsociety/posts/cve-2021-34527-printnightmare-mitigation-script
generic

CVE-2021-34527 - PrintNightmare - Detection Script - vsociety

https://www.vicarius.io/vsociety/posts/cve-2021-34527-printnightmare-detection-script
cert

VU#383432 - Microsoft Windows Print Spooler allows for RCE via AddPrinterDriverEx()

https://www.kb.cert.org/vuls/id/383432
microsoft Patch Available

Security Update Guide - Microsoft Security Response Center

Security Update Guide - Microsoft Security Response Center. Patch available via Microsoft Security Update

https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-34527
generic

Packet Storm

http://packetstormsecurity.com/files/167261/Print-Spooler-Remote-DLL-Injection.html

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

All Vendor Advisories

(1)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 59× in last 7d / 350× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 663 total refreshes for this CVE.

  1. 2026-07-23 02:01 UTCEG score recompute
  2. 2026-07-22 23:50 UTCEG score recompute
  3. 2026-07-22 23:50 UTCVendor advisory
  4. 2026-07-22 23:50 UTCGHSA enrichment
  5. 2026-07-22 22:48 UTCEG score recompute
  6. 2026-07-22 19:53 UTCGHSA enrichment
  7. 2026-07-22 19:40 UTCCISA KEV update
  8. 2026-07-22 15:55 UTCVendor advisory
  9. 2026-07-22 15:55 UTCGHSA enrichment
  10. 2026-07-22 11:56 UTCVendor advisory
  11. 2026-07-22 11:56 UTCGHSA enrichment
  12. 2026-07-22 07:59 UTCVendor advisory
  13. 2026-07-22 07:59 UTCGHSA enrichment
  14. 2026-07-22 04:01 UTCVendor advisory
  15. 2026-07-22 04:01 UTCGHSA enrichment
  16. 2026-07-22 00:03 UTCVendor advisory
  17. 2026-07-22 00:03 UTCGHSA enrichment
  18. 2026-07-21 20:02 UTCVendor advisory
  19. 2026-07-21 20:02 UTCGHSA enrichment
  20. 2026-07-21 16:04 UTCEG score recompute
  21. 2026-07-21 16:04 UTCVendor advisory
  22. 2026-07-21 16:04 UTCGHSA enrichment
  23. 2026-07-21 15:22 UTCEPSS rescore
  24. 2026-07-21 15:22 UTCEPSS rescore
  25. 2026-07-21 14:37 UTCCISA KEV update
Show 75 more
  1. 2026-07-21 12:07 UTCVendor advisory
  2. 2026-07-21 12:07 UTCGHSA enrichment
  3. 2026-07-21 08:09 UTCVendor advisory
  4. 2026-07-21 08:09 UTCGHSA enrichment
  5. 2026-07-21 04:13 UTCVendor advisory
  6. 2026-07-21 04:12 UTCGHSA enrichment
  7. 2026-07-21 00:15 UTCVendor advisory
  8. 2026-07-21 00:15 UTCGHSA enrichment
  9. 2026-07-20 20:17 UTCEG score recompute
  10. 2026-07-20 20:17 UTCVendor advisory
  11. 2026-07-20 20:17 UTCGHSA enrichment
  12. 2026-07-20 17:05 UTCEPSS rescore
  13. 2026-07-20 16:18 UTCGHSA enrichment
  14. 2026-07-20 12:20 UTCGHSA enrichment
  15. 2026-07-20 08:23 UTCVendor advisory
  16. 2026-07-20 08:23 UTCGHSA enrichment
  17. 2026-07-20 04:26 UTCVendor advisory
  18. 2026-07-20 04:26 UTCGHSA enrichment
  19. 2026-07-20 00:29 UTCVendor advisory
  20. 2026-07-19 20:32 UTCVendor advisory
  21. 2026-07-19 20:31 UTCGHSA enrichment
  22. 2026-07-19 16:34 UTCVendor advisory
  23. 2026-07-19 16:34 UTCGHSA enrichment
  24. 2026-07-19 12:36 UTCVendor advisory
  25. 2026-07-19 12:36 UTCGHSA enrichment
  26. 2026-07-19 08:39 UTCVendor advisory
  27. 2026-07-19 08:39 UTCGHSA enrichment
  28. 2026-07-19 04:42 UTCVendor advisory
  29. 2026-07-19 04:42 UTCGHSA enrichment
  30. 2026-07-19 00:45 UTCGHSA enrichment
  31. 2026-07-18 20:48 UTCVendor advisory
  32. 2026-07-18 20:47 UTCGHSA enrichment
  33. 2026-07-18 16:49 UTCVendor advisory
  34. 2026-07-18 16:49 UTCGHSA enrichment
  35. 2026-07-18 12:52 UTCVendor advisory
  36. 2026-07-18 12:52 UTCGHSA enrichment
  37. 2026-07-18 08:54 UTCVendor advisory
  38. 2026-07-18 08:54 UTCGHSA enrichment
  39. 2026-07-18 04:56 UTCVendor advisory
  40. 2026-07-18 04:56 UTCGHSA enrichment
  41. 2026-07-18 00:59 UTCVendor advisory
  42. 2026-07-18 00:59 UTCGHSA enrichment
  43. 2026-07-17 21:02 UTCVendor advisory
  44. 2026-07-17 21:02 UTCGHSA enrichment
  45. 2026-07-17 17:05 UTCVendor advisory
  46. 2026-07-17 17:05 UTCGHSA enrichment
  47. 2026-07-17 13:08 UTCVendor advisory
  48. 2026-07-17 13:08 UTCGHSA enrichment
  49. 2026-07-17 09:11 UTCEG score recompute
  50. 2026-07-17 09:11 UTCVendor advisory
  51. 2026-07-17 09:11 UTCGHSA enrichment
  52. 2026-07-17 05:14 UTCVendor advisory
  53. 2026-07-17 05:14 UTCGHSA enrichment
  54. 2026-07-17 01:17 UTCVendor advisory
  55. 2026-07-17 01:16 UTCGHSA enrichment
  56. 2026-07-16 21:20 UTCVendor advisory
  57. 2026-07-16 21:20 UTCGHSA enrichment
  58. 2026-07-16 17:23 UTCVendor advisory
  59. 2026-07-16 17:23 UTCGHSA enrichment
  60. 2026-07-16 17:04 UTCCISA KEV update
  61. 2026-07-16 13:26 UTCVendor advisory
  62. 2026-07-16 13:26 UTCGHSA enrichment
  63. 2026-07-16 09:29 UTCVendor advisory
  64. 2026-07-16 09:29 UTCGHSA enrichment
  65. 2026-07-16 05:32 UTCVendor advisory
  66. 2026-07-16 05:32 UTCGHSA enrichment
  67. 2026-07-16 01:35 UTCVendor advisory
  68. 2026-07-16 01:35 UTCGHSA enrichment
  69. 2026-07-15 21:38 UTCVendor advisory
  70. 2026-07-15 21:38 UTCGHSA enrichment
  71. 2026-07-15 17:41 UTCVendor advisory
  72. 2026-07-15 17:41 UTCGHSA enrichment
  73. 2026-07-15 16:55 UTCEPSS rescore
  74. 2026-07-15 16:49 UTCCISA KEV update
  75. 2026-07-15 15:04 UTCCISA KEV update

Publicly available exploits

(10 references)

Working exploit code is in the public domain (10 GitHub PoCs). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • GitHub PoChackerhouse-opensource/cve-2021-34527
    First seen Sep 5, 2022

    CVE-2021-34527 AddPrinterDriverEx() Privilege Escalation

    Open source ↗
  • GitHub PoCm8sec/CVE-2021-34527
    First seen Aug 23, 2022

    PrintNightmare (CVE-2021-34527) PoC Exploit

    Open source ↗
  • GitHub PoCTomparte/PrintNightmare
    First seen Jul 28, 2021

    To fight against Windows security breach PrintNightmare! (CVE-2021-34527, CVE-2021-1675)

    Open source ↗
  • GitHub PoCdywhoami/CVE-2021-34527-Scanner-Based-On-cube0x0-POC
    First seen Jul 9, 2021
    Open source ↗
  • GitHub PoCpowershellpr0mpt/PrintNightmare-CVE-2021-34527
    First seen Jul 7, 2021

    How to fix the PrintNightmare vulnerability

    Open source ↗
  • GitHub PoCbyt3bl33d3r/ItWasAllADream
    First seen Jul 5, 2021

    A PrintNightmare (CVE-2021-34527) Python Scanner. Scan entire subnets for hosts vulnerable to the PrintNightmare RCE

    Open source ↗
  • GitHub PoCrdboboia/disable-RegisterSpoolerRemoteRpcEndPoint
    First seen Jul 5, 2021

    Workaround for Windows Print Spooler Remote Code Execution Vulnerability(CVE-2021-34527). See: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-34527

    Open source ↗
  • GitHub PoCnemo-wq/PrintNightmare-CVE-2021-34527
    First seen Jul 3, 2021

    PrintNightmare - Windows Print Spooler RCE/LPE Vulnerability (CVE-2021-34527, CVE-2021-1675) proof of concept exploits

    Open source ↗
  • GitHub PoCJohnHammond/CVE-2021-34527
    First seen Jul 2, 2021
    Open source ↗
  • GitHub PoCthomas-lauer/PrintNightmare
    First seen Jul 2, 2021

    Kritische Sicherheitslücke PrintNightmare CVE-2021-34527

    Open source ↗

Related CVEs(same vendor + same CWE)

Frequently asked(6)

What is CVE-2021-34527?
CVE-2021-34527 is a high vulnerability published on July 2, 2021. <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…
When was CVE-2021-34527 disclosed?
CVE-2021-34527 was first published in the National Vulnerability Database on July 2, 2021, with the most recent update on June 17, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-34527 actively exploited?
Yes. CISA added CVE-2021-34527 to the Known Exploited Vulnerabilities catalog on November 3, 2021, affecting Microsoft Windows. KEV listing indicates confirmed exploitation in the wild; this CVE warrants immediate patching attention.
What is the CVSS score of CVE-2021-34527?
CVE-2021-34527 has a CVSS v3 base score of 8.8 (NVD). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 9.0.
Which products are affected by CVE-2021-34527?
CVE-2021-34527 affects Microsoft Windows. The full affected-products list, including version ranges and fixed versions, is shown in the Affected Packages section of this page.
How do I remediate CVE-2021-34527?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-34527, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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