What is the CVSS score of CVE-2021-36934?

CVE-2021-36934 has a CVSS 3.1 base score of 7.8 (High). CVSS vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. EPSS exploitation probability: 90.1%.

Is there a public PoC exploit available for CVE-2021-36934?

Yes, a public proof-of-concept exploit is available for CVE-2021-36934. Prioritise patching immediately. EPSS: 90.1%.

How to fix or mitigate CVE-2021-36934?

Within 24 hours: Identify all affected systems and apply vendor patches immediately. Vendor patch is available.

Windows 10 1809 CVE-2021-36934

HIGH

2021-07-22 secure@microsoft.com

RCE Microsoft Windows 10 1809 Windows 10 1909 Windows 10 20H2 Windows 10 21H1 Windows 10 2004

7.8

CVSS 3.1 · Vendor: microsoft

View

Vulnerability Assessment

Impact	High risk (EPSS 90.1%). Any local user can extract all local account password hashes, computer account password, and DPAPI machine keys. These enable offline password cracking, pass-the-hash attacks, and decryption of user secrets.
Exploit ScenarioDerived	A standard user on a Windows 10 workstation accesses the VSS shadow copy using `cmd /c copy \\?\GLOBALROOT\Device\HarddiskVolumeShadowCopy1\Windows\System32\config\SAM .` to extract the SAM database. They then use mimikatz or secretsdump to extract password hashes and escalate to local administrator.

Act Now Prioritize within 24-48h. Why: In CISA KEV with patch available.

Exploited in the wild (CISA KEV) Patch available 90.1% exploitation probability (EPSS)

Get an e-mail when this CVE is exploited, patched or re-scored. Free account.

Alert me

AnalysisAIv1 – Mar 26, 2026

Windows contains an elevation of privilege vulnerability known as 'HiveNightmare' or 'SeriousSAM' where overly permissive ACLs on SAM, SYSTEM, and SECURITY registry hive shadow copies allow standard users to extract credentials.

Earlier versions of this analysis (1)

v1 Mar 26, 2026 - 11:19 CVSS 7.8

An elevation of privilege vulnerability in Windows caused by overly permissive Access Control Lists on system files (SAM, SYSTEM, SECURITY database) allows unprivileged users to read sensitive credential data from Volume Shadow Copies.

RemediationAI

Apply Microsoft security update. Delete existing VSS shadow copies that were created before patching: vssadmin delete shadows /all /quiet. Restrict access to VSS shadow copies via ACLs.

Affects your stack

Find out whether the stacks and servers you run are on an affected version.

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

Windows default ACLs on the SAM (Security Accounts Manager), SYSTEM, and SECURITY registry hive files grant read access to the BUILTIN\Users group on Volume Shadow Copy (VSS) snapshots. An attacker can read these files from the shadow copy, extract password hashes, cached credentials, and DPAPI keys without administrator privileges.

Know when Windows 10 1809 gets its next vulnerability

Watch products and get an email when something new is published
Check this CVE against your own stack and servers
Exploit and PoC references, threat intelligence from 22 sources

Continue with Google Continue with GitHub

No credit card · 7-day full trial

Severity by source

Vendor (microsoft) PRIMARY 7.8 HIGH

AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Primary rating from Vendor (microsoft) · only source for this CVE.

CVSS VectorVendor: microsoft

Attack Vector

Local

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Lifecycle Timeline

Added to CISA KEV

Feb 25, 2026 - 13:47 cisa

CISA KEV

Patch released

Feb 25, 2026 - 13:47 nvd

Patch available

CVE Published

Jul 22, 2021 - 07:15 nvd

HIGH 7.8

DescriptionCVE.org

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 <a href="https://support.microsoft.com/topic/1ceaa637-aaa3-4b58-a48b-baf72a2fa9e7">KB5005357- Delete Volume Shadow Copies</a>.

Executive ViewAI

Why It Matters

CVE-2021-36934 presents notable security risk rated CVSS 7.8. Exploitation could compromise the security of affected deployments. This vulnerability is actively exploited in the wild (KEV-listed) and requires immediate remediation. A patch is available and should be applied as part of regular vulnerability management.

Business Impact: Severe

Compensating Controls

Apply vendor patch. If immediate patching is not feasible: (1) Implement network-level access controls to limit exposure; (2) Enable enhanced monitoring and alerting; (3) Apply principle of least privilege.

Threat Intelligence Overview

Threat Score

9.3/10

Composite threat intelligence

EPSS Score

90.1%

Top 0% exploitable

Threat Intel

1 sources

Exploit

POC

Public exploit code exists

Data Quality

5 sources

Confidence: Medium

NVD

CVE.org

CISA KEV

EPSS POC (1) THREAT

VulDB

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue

Severity HIGH

CISA KEV Yes

Public POC Yes

EPSS 90.1%

Patch available Yes

Active threat Yes

Deciding rule

In CISA KEV with patch available

What every action level means

Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.

Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.

This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.

This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.

Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived

Out-of-Cycle

Exploitation· derived

Active

System Exposure· derived

Small

Automatable· derived

Human Impact

Very High

Priority Score

209

Low Medium High Critical

KEV: +50

EPSS: +90

CVSS: +39

PoC: +20

Weaponized: 0

Threat intel: +10

Gov advisory: 0

Attack Technique

Remote Code Execution CRITICAL

Remote Code Execution represents the critical moment when an attacker successfully runs arbitrary code on a target system without physical access.

Affected Products (CPE)CVE.org

cpe:2.3:o:microsoft:windows_10_1809:*:*:*:*:*:*:*:*

cpe:2.3:o:microsoft:windows_10_1909:*:*:*:*:*:*:*:*

cpe:2.3:o:microsoft:windows_10_2004:*:*:*:*:*:*:*:*

cpe:2.3:o:microsoft:windows_10_20h2:*:*:*:*:*:*:*:*

cpe:2.3:o:microsoft:windows_10_21h1:*:*:*:*:*:*:*:*

More in Windows 10 1809

View all

CVE-2021-40444 HIGH Act Now POC

8.8 Sep 15

Windows MSHTML component contains a remote code execution vulnerability that allows attackers to craft malicious ActiveX

CVE-2021-34527 HIGH Act Now POC

8.8 Jul 02

A remote code execution vulnerability exists when the Windows Print Spooler service improperly performs privileged fi

CVE-2022-30190 HIGH Act Now POC

7.8 Jun 01

Windows MSDT (Microsoft Support Diagnostic Tool) allows remote code execution when called via the ms-msdt URL protocol f

CVE-2021-1732 HIGH Act Now POC

7.8 Feb 25

Windows Win32k contains an out-of-bounds write vulnerability enabling local privilege escalation to SYSTEM, exploited by

CVE-2021-1675 HIGH Act Now POC

7.8 Jun 08

Windows Print Spooler Remote Code Execution Vulnerability. Rated high severity (CVSS 7.8), this vulnerability is no auth

CVE-2023-36884 HIGH Act Now POC

7.5 Jul 11

Windows Search Remote Code Execution Vulnerability. Rated high severity (CVSS 7.5), this vulnerability is remotely explo

CVE-2024-21412 HIGH Act Now POC

8.1 Feb 13

Internet Shortcut Files Security Feature Bypass Vulnerability. Rated high severity (CVSS 8.1), this vulnerability is rem

CVE-2023-44487 HIGH Act Now POC

7.5 Oct 10

Denial of service against HTTP/2 server implementations allows remote unauthenticated attackers to exhaust server resour

CVE-2024-30088 HIGH Act Now POC

7.0 Jun 11

Windows Kernel contains a TOCTOU race condition vulnerability allowing local privilege escalation, exploited by the OilR

CVE-2018-8453 HIGH Act Now POC

7.8 Oct 10

An elevation of privilege vulnerability exists in Windows when the Win32k component fails to properly handle objects in

CVE-2025-33053 HIGH Act Now POC

8.8 Jun 10

Windows Internet Shortcut Files (.url) contain an external control vulnerability (CVE-2025-33053, CVSS 8.8) that enables

CVE-2020-1054 HIGH Act Now POC

7.0 May 21

Elevation of privilege in the Windows Win32k kernel-mode driver allows a local, low-privileged attacker to escalate to S

Same technique RCE

View all

CVE-2021-44228 CRITICAL POC

10.0

CVE-2017-7269 CRITICAL POC

9.8

CVE-2022-47966 CRITICAL POC

9.8

CVE-2012-4681 CRITICAL POC

9.8

CVE-2023-3519 CRITICAL POC

9.8

CVE-2015-5119 CRITICAL POC

9.8

CVE-2016-4117 CRITICAL POC

9.8

CVE-2015-3113 CRITICAL POC

9.8

Threat IntelligenceMISP

Threat Actors

APT29

ATT&CK Techniques (observed)

T1068 - Exploitation for Privilege Escalation

Sources: MITRE ATT&CK, Metasploit/Nuclei

References

Advisories & patches

PATCH https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-36934 ADVISORY https://vuldb.com/vuln/178898 REF http://packetstormsecurity.com/files/164006/HiveNightmare-AKA-SeriousSAM.html REF https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-36934 REF https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-36934 REF https://www.kb.cert.org/vuls/id/506989

Search Externally

GitHub PoC

Exploit-DB PacketStorm Snyk Rapid7 Nuclei Templates Trickest PoC

Back