Background exploitation KEV catalog
CVE-2021-36934

Microsoft Windows SAM Local Privilege Escalation Vulnerability

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…

CheckOps priority index
6.9/10 Patch within 7 days
Severity7.8
Probability6.7
Exploitation3/5

Severity = CVSS. Probability = EPSS (FIRST). Exploitation = public signals: KEV, EUVD, ransomware, EPSS above 10 %, no account required.

EPSS · today 67.3% higher than 99.3% of CVEs
CVSS 3.1 7.8 AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:
Exploited for 1,728 days 10 Feb 2022
CISA due date 24 Feb 2022 for US federal agencies

Exploitation probability EPSS · FIRST

05010026 Sep05 Oct15 Oct24 Oct02 Nov
EPSS probability (%)Percentile among all CVEs

Exploitation signals 3 / 5

  • KEV catalog (CISA)10 Feb 2022
  • Exploited in EUVD (ENISA)10 Feb 2022
  • Used by ransomwareno
  • EPSS above 10 %67.3%
  • No account, over the networkno

What to do

Fix

Apply the vendor’s fix as soon as it is available.

CISA guidance: Apply updates per vendor instructions.

Meanwhile

Take the service off the internet or restrict access to it, watch the logs and look for signs of compromise.

Manufacturers (CRA)

Exploited vulnerability in your product: early warning to ENISA within 24 h, then notification within 72 h (Article 14 of the Cyber Resilience Act). The CRA explained

Description ENISA EUVD

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

Windows 10 Version 1809Windows 10 Version 20H2Windows 10 Version 1909Windows 10 Version 2004Windows 10 Version 21H1Windows
Affected versions
  • 10.0.17763.0 <10.0.17763.2114
  • 10.0.0 <10.0.19042.1165
  • 10.0.0 <10.0.18363.1734
  • 10.0.0 <10.0.17763.2114
  • 10.0.0 <10.0.19041.1165
  • 10.0.0 <10.0.19043.1165
Weaknesses (CWE)

Open source packages OSV

Affected libraries according to OSV, with fixed versions.

Timeline

  1. Published

  2. Exploitation reported (ENISA)

  3. Added to the KEV catalog

  4. CISA remediation due date

  5. EPSS peak: 67.3%

References

Other exploited vulnerabilities from the same vendor

  • CVE-2026-96951Microsoft Windows Command Injection Vulnerability
    5.6 · Actively exploited
  • CVE-2026-65660Microsoft SharePoint Code Injection Vulnerability
    5.0 · Actively exploited
  • CVE-2026-85880Microsoft Windows Heap-Based Buffer Overflow Vulnerability
    4.3 · Actively exploited
  • CVE-2026-81963Microsoft Windows Link Following Vulnerability
    4.3 · Actively exploited
  • CVE-2019-1068Microsoft SQL Server Remote Code Execution Vulnerability
    7.0 · Actively exploited
  • CVE-2026-69836Microsoft Entra
    5.3 · Actively exploited

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Sources: CISA KEV · ENISA EUVD · FIRST EPSS · OSV. Public data aggregated by CheckOps, updated automatically. Source texts remain the property of their authors. All exploited vulnerabilities