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.
CVE-2021-36934
“▲” beside the score: it is higher than NVD's CVSS score.
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. The 9.0 is the floor for confirmed exploitation, not an impact rating: this CVE's impact severity (EG Severity) is CVSS 7.8 HIGH under GitHub Security Advisory CVSS. Confidence: HIGH.
Also known asEUVD-2021-23510 (ENISA EUVD) · GHSA-x4m2-px5g-5q55 (GitHub Security Advisories)Source: ENISA EUVD
- Actively exploited in the wild (CISA-KEV) — the reason this is sooner than the SSVC decision on this page at low or medium mission impact
A fix is available — apply it.
- CVSS v3
- 7.8
- EG Score
- 9.0CRITICALhigh confidence
- EG Risk
- 75EG Risk 75/100
EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.
How it’s computed (value × EchelonGraph’s weight)Severity78% × 45%Impact severity (EG Severity): CVSS 7.8 of 10. Never the KEV-floored or EPSS-lifted EG Score.Exploitation100% × 40%Fixed at 100% for a CISA KEV listing: EchelonGraph's rule.Automatability0% × 15%CISA's SSVC Automatable value: no (Vulnrichment).SSVC (CISA's decision table, applied by EchelonGraph): Track at low, Attend at medium and Act at high mission impact.Exploitation active (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.Action: A fix is available. Apply it within your standard update timelines at low, sooner than that at medium and as soon as possible at high mission impact. - EPSS PROB
- 67%
- EPSS %ILE
- 99th
- KEV
- ⚠ Exploited
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (9.0): severity, escalated by confirmed exploitation. This CVE's 9.0 is the CISA KEV floor for confirmed exploitation, not an impact rating: its impact severity (EG Severity) is CVSS 7.8 HIGH.
- EG Severity
- 7.8 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
- EG Likelihood
- 67% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-01). FIRST's exploitation probability, not an EchelonGraph model.
- Confirmed exploitation
- CISA KEV and EG-KEV Tier 1 (exploited in the wild)Reported apart from the likelihood: an observed fact, not a probability.
- EG Priority
- SSVC Attend at medium mission impactTrack at low, Attend at medium and Act at high mission impact.CISA BOD 26-04: 3 days & forensic triage if the affected system is publicly exposed; 14 days if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.
SSVC (CISA's decision table, applied by EchelonGraph)Track at low, Attend at medium and Act at high mission impact.
A fix is available. Apply it within your standard update timelines at low, sooner than that at medium and as soon as possible at high mission impact.
Exploitation active (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table
BOD 26-04 (CISA's remediation timeline, Table 1)3 days & forensic triage if the affected system is publicly exposed; 14 days if it is not.
The score's inputs: In CISA KEV yes (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it
CISA required action“Apply updates per vendor instructions.”
Quoted verbatim from CISA's Known Exploited Vulnerabilities catalog. CISA directs it at US federal civilian executive branch agencies under Binding Operational Directive (BOD) 26-04, which replaced BOD 22-01 on 10 June 2026; it is not EchelonGraph's advice. CISA's notes: https://nvd.nist.gov/vuln/detail/CVE-2021-36934
Published
July 22, 2021
Last Modified
August 10, 2026
Advisory Details (5)
Auto-updated Oct 26, 2026Known 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-2021-36934VU#506989 - Microsoft Windows 10 gives unprivileged user access to system32\config files
https://www.kb.cert.org/vuls/id/506989Security Update Guide - Microsoft Security Response Center
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-36934Security Update Guide - Microsoft Security Response Center
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-36934Vendor Advisories for CVE-2021-36934(2)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
Weakness Classification(2)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 19× in last 7d / 172× in last 30d)
Each row is a time one of our pipelines fetched, updated or re-scored this CVE. 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. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.
Showing the most recent 100 of 1,665 refreshes on record for this CVE.
A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. None are among the latest 100 rows. The 1,565 oldest rows on record are not shown and were not checked, so the counts can still include repeats.
- 2026-11-01 17:28 UTCEG score recompute
- 2026-11-01 17:28 UTCVendor advisory
- 2026-11-01 17:28 UTCGHSA enrichmentGHSA-x4m2-px5g-5q55 · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-11-01 16:29 UTCEPSS rescoreEPSS 67% · 99th percentile
- 2026-10-31 16:28 UTCEPSS rescoreEPSS 67% · 99th percentile
- 2026-10-31 15:33 UTCEG score recompute
- 2026-10-31 15:33 UTCVendor advisory
- 2026-10-31 15:33 UTCGHSA enrichmentGHSA-x4m2-px5g-5q55 · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-30 13:38 UTCEG score recompute
- 2026-10-30 13:38 UTCVendor advisory
- 2026-10-30 13:38 UTCGHSA enrichmentGHSA-x4m2-px5g-5q55 · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-29 16:29 UTCEPSS rescoreEPSS 67% · 99th percentile
- 2026-10-29 11:42 UTCEG score recompute
- 2026-10-29 11:42 UTCGHSA enrichmentGHSA-x4m2-px5g-5q55 · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-28 09:47 UTCEG score recompute
- 2026-10-28 09:47 UTCGHSA enrichmentGHSA-x4m2-px5g-5q55 · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-27 16:28 UTCEPSS rescoreEPSS 67% · 99th percentile
- 2026-10-27 07:52 UTCEG score recompute
- 2026-10-27 07:52 UTCGHSA enrichmentGHSA-x4m2-px5g-5q55 · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-26 05:57 UTCGHSA enrichmentGHSA-x4m2-px5g-5q55 · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-25 18:25 UTCEG score recompute
- 2026-10-25 16:28 UTCEPSS rescoreEPSS 67% · 99th percentile
- 2026-10-25 04:01 UTCEG score recompute
- 2026-10-25 04:01 UTCVendor advisory
- 2026-10-25 04:01 UTCGHSA enrichmentGHSA-x4m2-px5g-5q55 · GitHub severity HIGH · GitHub CVSS 7.8
Show 75 moreShow fewer
- 2026-10-24 16:28 UTCEPSS rescoreEPSS 67% · 99th percentile
- 2026-10-24 02:06 UTCEG score recompute
- 2026-10-24 02:06 UTCGHSA enrichmentGHSA-x4m2-px5g-5q55 · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-23 16:28 UTCEPSS rescoreEPSS 67% · 99th percentile
- 2026-10-23 00:11 UTCEG score recompute
- 2026-10-23 00:11 UTCGHSA enrichmentGHSA-x4m2-px5g-5q55 · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-21 22:13 UTCEG score recompute
- 2026-10-21 22:13 UTCVendor advisory
- 2026-10-21 22:13 UTCGHSA enrichmentGHSA-x4m2-px5g-5q55 · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-21 16:28 UTCEPSS rescoreEPSS 67% · 99th percentile
- 2026-10-20 20:17 UTCEG score recompute
- 2026-10-20 20:17 UTCVendor advisory
- 2026-10-20 20:17 UTCGHSA enrichmentGHSA-x4m2-px5g-5q55 · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-20 16:28 UTCEPSS rescoreEPSS 67% · 99th percentile
- 2026-10-19 18:21 UTCEG score recompute
- 2026-10-19 18:21 UTCVendor advisory
- 2026-10-19 18:21 UTCGHSA enrichmentGHSA-x4m2-px5g-5q55 · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-19 16:28 UTCEPSS rescoreEPSS 67% · 99th percentile
- 2026-10-18 16:26 UTCVendor advisory
- 2026-10-18 16:26 UTCGHSA enrichmentGHSA-x4m2-px5g-5q55 · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-18 08:57 UTCEG score recompute
- 2026-10-17 17:26 UTCEG score recompute
- 2026-10-17 17:26 UTCVendor advisory
- 2026-10-17 17:26 UTCGHSA enrichmentGHSA-x4m2-px5g-5q55 · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-17 16:29 UTCEPSS rescoreEPSS 67% · 99th percentile
- 2026-10-16 16:33 UTCEPSS rescoreEPSS 67% · 99th percentile
- 2026-10-16 15:29 UTCEG score recompute
- 2026-10-16 15:29 UTCGHSA enrichmentGHSA-x4m2-px5g-5q55 · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-15 13:32 UTCEG score recompute
- 2026-10-15 13:31 UTCGHSA enrichmentGHSA-x4m2-px5g-5q55 · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-14 16:28 UTCEPSS rescoreEPSS 67% · 99th percentile
- 2026-10-14 11:34 UTCEG score recompute
- 2026-10-14 11:34 UTCGHSA enrichmentGHSA-x4m2-px5g-5q55 · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-13 16:28 UTCEPSS rescoreEPSS 67% · 99th percentile
- 2026-10-13 09:39 UTCVendor advisory
- 2026-10-13 09:38 UTCGHSA enrichmentGHSA-x4m2-px5g-5q55 · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-12 19:13 UTCEG score recompute
- 2026-10-12 07:43 UTCVendor advisory
- 2026-10-12 07:43 UTCGHSA enrichmentGHSA-x4m2-px5g-5q55 · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-12 03:20 UTCVendor advisory
- 2026-10-12 03:20 UTCGHSA enrichmentGHSA-x4m2-px5g-5q55 · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-11 22:54 UTCEG score recompute
- 2026-10-11 22:54 UTCVendor advisory
- 2026-10-11 22:53 UTCGHSA enrichmentGHSA-x4m2-px5g-5q55 · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-11 18:28 UTCEG score recompute
- 2026-10-11 18:28 UTCVendor advisory
- 2026-10-11 18:28 UTCGHSA enrichmentGHSA-x4m2-px5g-5q55 · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-11 14:04 UTCEG score recompute
- 2026-10-11 14:04 UTCVendor advisory
- 2026-10-11 14:04 UTCGHSA enrichmentGHSA-x4m2-px5g-5q55 · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-11 09:42 UTCVendor advisory
- 2026-10-11 09:42 UTCGHSA enrichmentGHSA-x4m2-px5g-5q55 · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-11 05:17 UTCVendor advisory
- 2026-10-11 05:17 UTCGHSA enrichmentGHSA-x4m2-px5g-5q55 · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-11 00:55 UTCVendor advisory
- 2026-10-11 00:54 UTCGHSA enrichmentGHSA-x4m2-px5g-5q55 · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-10 20:30 UTCEG score recompute
- 2026-10-10 20:30 UTCVendor advisory
- 2026-10-10 20:30 UTCGHSA enrichmentGHSA-x4m2-px5g-5q55 · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-10 19:56 UTCEPSS rescoreEPSS 67% · 99th percentile
- 2026-10-10 16:08 UTCGHSA enrichmentGHSA-x4m2-px5g-5q55 · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-10 11:42 UTCVendor advisory
- 2026-10-10 11:42 UTCGHSA enrichmentGHSA-x4m2-px5g-5q55 · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-10 07:20 UTCVendor advisory
- 2026-10-10 07:20 UTCGHSA enrichmentGHSA-x4m2-px5g-5q55 · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-10 02:57 UTCVendor advisory
- 2026-10-10 02:57 UTCGHSA enrichmentGHSA-x4m2-px5g-5q55 · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-09 22:34 UTCEG score recompute
- 2026-10-09 22:34 UTCVendor advisory
- 2026-10-09 22:34 UTCGHSA enrichmentGHSA-x4m2-px5g-5q55 · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-09 20:04 UTCEPSS rescoreEPSS 67% · 99th percentile
- 2026-10-09 18:11 UTCVendor advisory
- 2026-10-09 18:11 UTCGHSA enrichmentGHSA-x4m2-px5g-5q55 · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-09 13:48 UTCVendor advisory
- 2026-10-09 13:48 UTCGHSA enrichmentGHSA-x4m2-px5g-5q55 · GitHub severity HIGH · GitHub CVSS 7.8
Publicly available exploits
(11 references, 10 shown)Public exploit code is referenced for this CVE (1 Metasploit module, 9 GitHub PoCs), as is 1 GitHub checker repository. A GitHub repository named or described as a checker or scanner checks whether a system is affected; it is not necessarily exploit code. Defenders should treat patch urgency accordingly.
- Metasploitpost/windows/gather/credentials/windows_sam_hivenightmare✓ verifiedPublished Jul 29, 2021
Windows SAM secrets leak - HiveNightmare
Open source ↗ - GitHub PoCchron1k/oxide_hivePublished Aug 12, 2021
Exploit for CVE-2021-36934
Open source ↗ - GitHub PoCexploitblizzard/CVE-2021-36934Published Jul 27, 2021
HiveNightmare aka SeriousSAM
Open source ↗ - GitHub PoCSp00kySkelet0n/PyNightmarePublished Jul 25, 2021
PoC for CVE-2021-36934 Aka HiveNightmare/SeriousSAM written in python3
Open source ↗ - GitHub PoCPreventions/CVE-2021-36934Published Jul 24, 2021
C# PoC for CVE-2021-36934/HiveNightmare/SeriousSAM
Open source ↗ - GitHub PoCromarroca/SeriousSamPublished Jul 22, 2021
HiveNightmare a.k.a. SeriousSam Local Privilege Escalation in Windows – CVE-2021-36934
Open source ↗ - GitHub PoCWh04m1001/VSSCopyPublished Jul 22, 2021
Small and dirty PoC for CVE-2021-36934
Open source ↗ - GitHub PoCWiredPulse/Invoke-HiveNightmarePublished 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 checkern3tsurge/CVE-2021-36934Published Jul 21, 2021
Detection and Mitigation script for CVE-2021-36934 (HiveNightmare aka. SeriousSam)
Open source ↗ - GitHub PoCJoranSlingerland/CVE-2021-36934Published Jul 21, 2021
Fix for the CVE-2021-36934
Open source ↗
Related CVEs(same CWE)
Frequently asked(6)
What is CVE-2021-36934?
When was CVE-2021-36934 made public?
Is CVE-2021-36934 actively exploited?
What is the CVSS score of CVE-2021-36934?
Which products are affected by CVE-2021-36934?
How do I remediate CVE-2021-36934?
Dependency Blast Radius
Explore the affected products and dependency analysis for CVE-2021-36934
Is Your Infrastructure Affected by CVE-2021-36934?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.