CVE-2021-36942: Microsoft Windows Local Security Authority (LSA) Spoofing Vulnerability

Is it exploited?

Yes. CISA added it to the Known Exploited Vulnerabilities catalog on 3 Nov 2021, 83 days after the CVE record was published.

How likely is exploitation in the next 30 days?

66%

EPSS score, percentile 99.3 of all scored records

How severe?

7.5 High

CVSS v3.1 base score, given by the CNA

What should I do?

CISA deadline 17 Nov 2021. Apply updates per vendor instructions.

Advisories and patches (1)

Which versions are affected?

Affected

• from 6.1.7601.0 to before 6.1.7601.25685
• from 6.1.7601.0 to before 6.1.7601.25685
• from 6.0.6003.0 to before 6.0.6003.21192
• from 6.0.6003.0 to before 6.0.6003.21192
• from 6.2.9200.0 to before 6.2.9200.23435
• from 6.2.9200.0 to before 6.2.9200.23435

and 8 more in the table below

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: 17 November 2021.

Advisories and patches

• Windows LSA Spoofing Vulnerability (Vendor advisory, Patch)

Linked from CISA's catalog entry

• https://nvd.nist.gov/vuln/detail/CVE-2021-36942

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

Microsoft Windows Local Security Authority (LSA) contains a spoofing vulnerability allowing an unauthenticated attacker to call a method on the LSARPC interface and coerce the domain controller to authenticate against another server using NTLM.

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

• CISA added CVE-2021-36942 to its Known Exploited Vulnerabilities (KEV) catalog on 3 Nov 2021.
• CISA marks it as known to be used in ransomware campaigns.
• The due date CISA sets for the required action is 17 Nov 2021.
• The CVE record was published on 12 Aug 2021, 83 days before it was added to KEV.
• The CVE record carries a CVSS v3.1 base score of 7.5 (High), given by its CNA.
• FIRST's EPSS model puts the probability of exploitation in the next 30 days at 66% (percentile 99.3), as of 28 Oct 2026.
• CISA's SSVC assessment in the CVE record: exploitation active, automatable yes, 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 LSA Spoofing Vulnerability

Windows LSA Spoofing Vulnerability

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

Weakness

• CWE-749

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

Timeline

More exploited Microsoft vulnerabilities

• CVE-2026-96951: Microsoft Windows Command Injection Vulnerability (added 13 Oct 2026)
• CVE-2026-65660: Microsoft SharePoint Code Injection Vulnerability (added 25 Sep 2026)
• CVE-2026-81963: Microsoft Windows Link Following Vulnerability (added 8 Sep 2026)
• CVE-2026-85880: Microsoft Windows Heap-Based Buffer Overflow Vulnerability (added 8 Sep 2026)
• CVE-2019-1068: Microsoft SQL Server Remote Code Execution Vulnerability (added 26 Aug 2026)
• CVE-2026-33824: Microsoft Internet Key Exchange (IKE) Service Extensions Double Free Vulnerability (added 18 Aug 2026)