CVE-2021-36934

CRITICALNVD 7.89.0▲
EchelonGraph scoreHIGH confidence

Score elevated to 9.0 because this CVE is listed on the CISA Known Exploited Vulnerabilities catalog (added 2022-02-10), indicating real-world exploitation has been confirmed by US federal agencies. NVD baseline CVSS 7.8 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
9.0EG
EchelonGraph verdictPatch nowTreat as an emergency — this is being exploited.
  • Actively exploited in the wild (CISA-KEV)
CISA-KEV: ExploitedEPSS PROB: 67%CVSS: 7.8Exploit: cisa kev · ssvc active · Metasploit · epss top5pct · epss high · public exploitExposed: 0

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

An elevation of privilege vulnerability exists because of overly permissive Access Control Lists (ACLs) on multiple system files, including the Security Accounts Manager (SAM) database. 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. An attacker must have the ability to execute code on a victim system to exploit this vulnerability. After installing this security update, you must manually delete all shadow copies of system files, including the SAM database, to fully mitigate this vulnerabilty. Simply installing this security update will not fully mitigate this vulnerability. See KB5005357- Delete Volume Shadow Copies.

CVSS v3
7.8
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 PROB
67%
EPSS %ILE
99%
KEV
⚠ Exploited

Published

July 22, 2021

Last Modified

February 25, 2026

Advisory Details (4)

Auto-updated Jun 4, 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-2021-36934
cert

VU#506989 - Microsoft Windows 10 gives unprivileged user access to system32\config files

https://www.kb.cert.org/vuls/id/506989
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-2021-36934
generic

Packet Storm

http://packetstormsecurity.com/files/164006/HiveNightmare-AKA-SeriousSAM.html

Weakness Classification(2)

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 / 330× 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 671 total refreshes for this CVE.

  1. 2026-07-28 15:33 UTCEPSS rescore
  2. 2026-07-28 15:28 UTCVendor advisory
  3. 2026-07-28 15:28 UTCGHSA enrichment
  4. 2026-07-28 11:06 UTCVendor advisory
  5. 2026-07-28 11:06 UTCGHSA enrichment
  6. 2026-07-28 06:42 UTCVendor advisory
  7. 2026-07-28 06:42 UTCGHSA enrichment
  8. 2026-07-28 02:19 UTCVendor advisory
  9. 2026-07-28 02:19 UTCGHSA enrichment
  10. 2026-07-27 21:57 UTCVendor advisory
  11. 2026-07-27 21:57 UTCGHSA enrichment
  12. 2026-07-27 19:24 UTCCISA KEV update
  13. 2026-07-27 17:34 UTCVendor advisory
  14. 2026-07-27 17:34 UTCGHSA enrichment
  15. 2026-07-27 17:17 UTCCISA KEV update
  16. 2026-07-27 13:12 UTCVendor advisory
  17. 2026-07-27 13:12 UTCGHSA enrichment
  18. 2026-07-27 08:49 UTCVendor advisory
  19. 2026-07-27 08:49 UTCGHSA enrichment
  20. 2026-07-27 04:27 UTCVendor advisory
  21. 2026-07-27 04:27 UTCGHSA enrichment
  22. 2026-07-27 00:03 UTCVendor advisory
  23. 2026-07-27 00:03 UTCGHSA enrichment
  24. 2026-07-26 19:38 UTCVendor advisory
  25. 2026-07-26 19:38 UTCGHSA enrichment
Show 75 more
  1. 2026-07-26 15:15 UTCEG score recompute
  2. 2026-07-26 15:15 UTCVendor advisory
  3. 2026-07-26 15:15 UTCGHSA enrichment
  4. 2026-07-26 14:52 UTCEPSS rescore
  5. 2026-07-26 14:52 UTCEPSS rescore
  6. 2026-07-26 10:52 UTCEG score recompute
  7. 2026-07-26 10:52 UTCVendor advisory
  8. 2026-07-26 10:52 UTCGHSA enrichment
  9. 2026-07-26 06:30 UTCVendor advisory
  10. 2026-07-26 06:30 UTCGHSA enrichment
  11. 2026-07-26 02:08 UTCEG score recompute
  12. 2026-07-26 02:08 UTCVendor advisory
  13. 2026-07-26 02:07 UTCGHSA enrichment
  14. 2026-07-25 14:15 UTCEPSS rescore
  15. 2026-07-24 14:15 UTCEPSS rescore
  16. 2026-07-23 02:03 UTCEG score recompute
  17. 2026-07-22 22:11 UTCEG score recompute
  18. 2026-07-22 22:11 UTCVendor advisory
  19. 2026-07-22 22:10 UTCGHSA enrichment
  20. 2026-07-22 19:40 UTCCISA KEV update
  21. 2026-07-22 17:47 UTCEG score recompute
  22. 2026-07-22 17:47 UTCGHSA enrichment
  23. 2026-07-22 14:06 UTCEPSS rescore
  24. 2026-07-22 14:06 UTCEPSS rescore
  25. 2026-07-22 13:24 UTCVendor advisory
  26. 2026-07-22 13:24 UTCGHSA enrichment
  27. 2026-07-22 09:01 UTCVendor advisory
  28. 2026-07-22 09:01 UTCGHSA enrichment
  29. 2026-07-22 04:39 UTCVendor advisory
  30. 2026-07-22 04:39 UTCGHSA enrichment
  31. 2026-07-22 00:16 UTCVendor advisory
  32. 2026-07-22 00:16 UTCGHSA enrichment
  33. 2026-07-21 19:52 UTCVendor advisory
  34. 2026-07-21 19:51 UTCGHSA enrichment
  35. 2026-07-21 15:27 UTCVendor advisory
  36. 2026-07-21 15:27 UTCGHSA enrichment
  37. 2026-07-21 14:37 UTCCISA KEV update
  38. 2026-07-21 11:02 UTCVendor advisory
  39. 2026-07-21 11:01 UTCGHSA enrichment
  40. 2026-07-21 06:37 UTCVendor advisory
  41. 2026-07-21 06:37 UTCGHSA enrichment
  42. 2026-07-21 02:15 UTCVendor advisory
  43. 2026-07-21 02:15 UTCGHSA enrichment
  44. 2026-07-20 21:53 UTCVendor advisory
  45. 2026-07-20 21:53 UTCGHSA enrichment
  46. 2026-07-20 17:30 UTCEG score recompute
  47. 2026-07-20 17:30 UTCVendor advisory
  48. 2026-07-20 17:30 UTCGHSA enrichment
  49. 2026-07-20 17:05 UTCEPSS rescore
  50. 2026-07-20 13:07 UTCGHSA enrichment
  51. 2026-07-20 08:44 UTCVendor advisory
  52. 2026-07-20 08:44 UTCGHSA enrichment
  53. 2026-07-20 04:21 UTCVendor advisory
  54. 2026-07-20 04:21 UTCGHSA enrichment
  55. 2026-07-19 23:58 UTCVendor advisory
  56. 2026-07-19 23:58 UTCGHSA enrichment
  57. 2026-07-19 19:35 UTCVendor advisory
  58. 2026-07-19 19:35 UTCGHSA enrichment
  59. 2026-07-19 15:12 UTCEG score recompute
  60. 2026-07-19 15:12 UTCVendor advisory
  61. 2026-07-19 15:12 UTCGHSA enrichment
  62. 2026-07-19 14:29 UTCEPSS rescore
  63. 2026-07-19 14:29 UTCEPSS rescore
  64. 2026-07-19 10:49 UTCVendor advisory
  65. 2026-07-19 10:49 UTCGHSA enrichment
  66. 2026-07-19 06:27 UTCVendor advisory
  67. 2026-07-19 06:27 UTCGHSA enrichment
  68. 2026-07-19 02:04 UTCGHSA enrichment
  69. 2026-07-18 21:41 UTCVendor advisory
  70. 2026-07-18 21:41 UTCGHSA enrichment
  71. 2026-07-18 17:18 UTCVendor advisory
  72. 2026-07-18 17:18 UTCGHSA enrichment
  73. 2026-07-18 12:56 UTCVendor advisory
  74. 2026-07-18 12:56 UTCGHSA enrichment
  75. 2026-07-18 08:33 UTCVendor advisory

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 PoCchron1k/oxide_hive
    First seen Aug 12, 2021

    Exploit for CVE-2021-36934

    Open source ↗
  • GitHub PoCexploitblizzard/CVE-2021-36934
    First seen Jul 27, 2021

    HiveNightmare aka SeriousSAM

    Open source ↗
  • GitHub PoCSp00kySkelet0n/PyNightmare
    First seen Jul 25, 2021

    PoC for CVE-2021-36934 Aka HiveNightmare/SeriousSAM written in python3

    Open source ↗
  • GitHub PoCPreventions/CVE-2021-36934
    First seen Jul 24, 2021

    C# PoC for CVE-2021-36934/HiveNightmare/SeriousSAM

    Open source ↗
  • GitHub PoCromarroca/SeriousSam
    First seen Jul 22, 2021

    HiveNightmare a.k.a. SeriousSam Local Privilege Escalation in Windows – CVE-2021-36934

    Open source ↗
  • GitHub PoCWiredPulse/Invoke-HiveNightmare
    First seen Jul 22, 2021

    PoC for CVE-2021-36934, which enables a standard user to be able to retrieve the SAM, Security, and Software Registry hives in Windows 10 version 1809 or newer

    Open source ↗
  • GitHub PoCWh04m1001/VSSCopy
    First seen Jul 22, 2021

    Small and dirty PoC for CVE-2021-36934

    Open source ↗
  • GitHub PoCJoranSlingerland/CVE-2021-36934
    First seen Jul 21, 2021

    Fix for the CVE-2021-36934

    Open source ↗
  • GitHub PoCn3tsurge/CVE-2021-36934
    First seen Jul 21, 2021

    Detection and Mitigation script for CVE-2021-36934 (HiveNightmare aka. SeriousSam)

    Open source ↗
  • GitHub PoCHuskyHacks/ShadowSteal
    First seen Jul 20, 2021

    Pure Nim implementation for exploiting CVE-2021-36934, the SeriousSAM local privilege escalation

    Open source ↗

Related CVEs(same vendor + same CWE)

Frequently asked(6)

What is CVE-2021-36934?
CVE-2021-36934 is a critical vulnerability published on July 22, 2021. <p>An elevation of privilege vulnerability exists because of overly permissive Access Control Lists (ACLs) on multiple system files, including the Security Accounts Manager (SAM) database. An attacker who successfully exploited this vulnerability could run arbitrary code with SYSTEM privileges. An…
When was CVE-2021-36934 disclosed?
CVE-2021-36934 was first published in the National Vulnerability Database on July 22, 2021, with the most recent update on February 25, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-36934 actively exploited?
Yes. CISA added CVE-2021-36934 to the Known Exploited Vulnerabilities catalog on February 10, 2022, affecting Microsoft Windows. KEV listing indicates confirmed exploitation in the wild; this CVE warrants immediate patching attention.
What is the CVSS score of CVE-2021-36934?
CVE-2021-36934 has a CVSS v3 base score of 7.8 (NVD). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 9.0.
Which products are affected by CVE-2021-36934?
CVE-2021-36934 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-2021-36934?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-36934, 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

Explore the affected products and dependency analysis for CVE-2021-36934

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