How severe is CVE-2021-36934?

CVE-2021-36934 has a CVSS score of 7.8/10, rated HIGH. Immediate patching is strongly recommended.

Which products are affected by CVE-2021-36934?

Affected package information for CVE-2021-36934 is not yet fully mapped. Check the official advisory links for details.

How do I patch CVE-2021-36934?

Apply the microsoft windows 10 20h2 security patch or hotfix for CVE-2021-36934 on the affected version, following the vendor advisory for your exact build.

How do I detect CVE-2021-36934 across my infrastructure?

Inventory every microsoft windows 10 20h2 deployment and check each version against the affected-products list above. Because the exploit targets the running system rather than your application code, also watch for remote code execution at the network and runtime layer — O3 flags the exploit behaviour from runtime telemetry and egress traffic even before a vulnerable build is confirmed.

How do I mitigate CVE-2021-36934 if there is no patch (or I can't update yet)?

Cut exposure now: restrict the management/admin interface to trusted networks, segment the device, and apply the vendor's recommended configuration mitigations and any WAF/IPS signature. O3's runtime protection blocks the exploit chain at execution, holding the line on unpatched or end-of-life systems until you can patch.

How does O3 Security protect against CVE-2021-36934?

O3 detects and blocks CVE-2021-36934 exploitation at runtime: eBPF exploit-chain detection, plus L7 egress monitoring that catches the post-exploitation callback and severs the attacker's outbound channel.

Is CVE-2021-36934 actively exploited in the wild?

Yes. There are 24 known exploit references for CVE-2021-36934, including 1 documented proof-of-concept exploit on Exploit-DB and 13 in-the-wild exploitations observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2021-36934?

CVE-2021-36934 has an EPSS (Exploit Prediction Scoring System) score of 67.3%, placing it in the 99th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. A score above 50% indicates significantly elevated exploitation risk — immediate patching is strongly recommended.

Is CVE-2021-36934 in the CISA Known Exploited Vulnerabilities catalog?

Yes. CVE-2021-36934 (Microsoft Windows SAM Local Privilege Escalation Vulnerability) was added to CISA's Known Exploited Vulnerabilities (KEV) catalog on 2022-02-10. CISA required all US federal civilian agencies to remediate this vulnerability by 2022-02-24. The required action was: Apply updates per vendor instructions. Being listed in the KEV catalog is the strongest possible confirmation of active exploitation — treat this as a critical priority.

Which products and versions are affected by CVE-2021-36934?

CVE-2021-36934 affects microsoft windows 10 20h2; microsoft windows 10 21h1; microsoft windows 10 1809; microsoft windows 10 1909, and 1 more product(s). Check the affected-products list on this page against your deployed version to confirm exposure.

When was CVE-2021-36934 published, and has it been updated?

CVE-2021-36934 was published on July 22, 2021 and was last updated on June 17, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

CVE-2021-36934: Windows 10 20h2 Remote Code Execution (High 7.8)

EPSS Exploitation Probability

via FIRST.org ↗

67.3%probability of exploitation in next 30 days

High Risk99th percentile0.00%

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Description

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>.

Affected Products

5 products · 5 configurations

OS

windows 10 20h2microsoft

< 10.0.19042.1165

range

OS

windows 10 21h1microsoft

< 10.0.19043.1165

range

OS

windows 10 1809microsoft

< 10.0.17763.2114

range

OS

windows 10 1909microsoft

< 10.0.18363.1734

range

OS

windows 10 2004microsoft

< 10.0.19041.1165

range

Detection & mitigation playbook

Vendor / appliance

Detect
Inventory every microsoft windows 10 20h2 deployment and check each version against the affected-products list above. Because the exploit targets the running system rather than your application code, also watch for remote code execution at the network and runtime layer — O3 flags the exploit behaviour from runtime telemetry and egress traffic even before a vulnerable build is confirmed.
Fix
Apply the microsoft windows 10 20h2 security patch or hotfix for CVE-2021-36934 on the affected version, following the vendor advisory for your exact build.
Workarounds
Cut exposure now: restrict the management/admin interface to trusted networks, segment the device, and apply the vendor's recommended configuration mitigations and any WAF/IPS signature. O3's runtime protection blocks the exploit chain at execution, holding the line on unpatched or end-of-life systems until you can patch.
How O3 protects you
O3 detects and blocks CVE-2021-36934 exploitation at runtime: eBPF exploit-chain detection, plus L7 egress monitoring that catches the post-exploitation callback and severs the attacker's outbound channel.

Tailored to CVE-2021-36934. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

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

O3 Security · Runtime Protection

Is CVE-2021-36934 being exploited in your environment?

O3's eBPF runtime sensors and L7 egress monitoring detect and block the CVE-2021-36934 exploit chain at execution — protecting unpatched and end-of-life systems until the vendor patch is applied.

Protect my workloads How runtime protection works

CVE-2021-36934

EPSS Exploitation Probability

Description

Affected Products

Detection & mitigation playbook

Detect

Fix

Workarounds

How O3 protects you

Frequently Asked Questions

Is CVE-2021-36934 being exploited in your environment?