CVE-2021-36934: Microsoft Windows SAM Local Privilege Escalation Vulnerability

High severity, CVSS 7.8. Actively exploited: in CISA KEV since 2022-02-10. EPSS: 67.3% chance of exploitation in the next 30 days.

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.

Affected products

• Microsoft Windows 10 1809: before 10.0.17763.2114 (fixed in 10.0.17763.2114)
• Microsoft Windows 10 1909: before 10.0.18363.1734 (fixed in 10.0.18363.1734)
• Microsoft Windows 10 2004: before 10.0.19041.1165 (fixed in 10.0.19041.1165)
• Microsoft Windows 10 20h2: before 10.0.19042.1165 (fixed in 10.0.19042.1165)
• Microsoft Windows 10 21h1: before 10.0.19043.1165 (fixed in 10.0.19043.1165)

Published 2021-07-22. Last modified 2026-08-10.