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

Is it exploited?

Yes. CISA added it to the Known Exploited Vulnerabilities catalog on 10 Feb 2022, 203 days after the CVE record was published.

How likely is exploitation in the next 30 days?

67.3%

EPSS score, percentile 99.3 of all scored records

How severe?

7.8 High

CVSS v3.1 base score, given by the CNA

What should I do?

Required action (CISA), due 24 Feb 2022: Apply updates per vendor instructions.

Advisories and patches (1)

Which versions are affected?

Affected: 10.0.17763.0 up to, not including, 10.0.17763.2114; 10.0.0 up to, not including, 10.0.17763.2114; 10.0.0 up to, not including, 10.0.18363.1734; 10.0.0 up to, not including, 10.0.19041.1165; 10.0.0 up to, not including, 10.0.19042.1165; 10.0.0 up to, not including, 10.0.19043.1165

Versions by product

Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

What to do

CISA due date for this action: 24 February 2022.

Advisories and patches

• Windows Elevation of Privilege Vulnerability (Vendor advisory, Patch)

Linked from CISA's catalog entry

• https://nvd.nist.gov/vuln/detail/CVE-2021-36934

Affected products and versions

As listed in the CVE record.

Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

About this vulnerability

If a Volume Shadow Copy (VSS) shadow copy of the system drive is available, users can read the SAM file which would allow any user to escalate privileges to SYSTEM level.

Summary: CISA's KEV catalog, as of 28 Oct 2026.

• CISA added CVE-2021-36934 to its Known Exploited Vulnerabilities (KEV) catalog on 10 Feb 2022.
• CISA's ransomware flag for this entry is "Unknown": no evidence of ransomware use in the catalog, which is not proof of none.
• The due date CISA sets for the required action is 24 Feb 2022.
• The CVE record was published on 22 Jul 2021, 203 days before it was added to KEV.
• The CVE record carries a CVSS v3.1 base score of 7.8 (High), given by its CNA.
• FIRST's EPSS model puts the probability of exploitation in the next 30 days at 67.3% (percentile 99.3), as of 28 Oct 2026.
• CISA's SSVC assessment in the CVE record: exploitation active, automatable no, technical impact total.

Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026. About the data.

Description

Windows Elevation of Privilege 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 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.

Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

Weakness

• CWE-1220

CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record and the KEV entry.

Timeline

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