CVE-2021-36942
KEVRansomware UseMicrosoft Windows Local Security Authority (LSA) Spoofing Vulnerability
Description
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.
Windows LSA Spoofing Vulnerability
CVSS 3.1 vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:NPublishedAug 12, 2021
Last modifiedAug 10, 2026
Added to KEVNov 3, 2021
Remediation dueNov 17, 2021
References
- msrc.microsoft.com/update-guide/vulnerability/CVE-2021-36942PatchVendor Advisory
- portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-36942PatchVendor Advisory
- kb.cert.org/vuls/id/405600ExploitThird Party Advisory
- cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-36942US Government Resource
0 recent articles mention this CVE
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Risk assessment · Critical
Actively exploited and used by ransomware crews. Patch immediately.
- Exploitation
- Confirmed in the wild (CISA KEV)
- Federal remediation deadline
- Overdue by 1805 days
- Ransomware
- Used in known ransomware campaigns
- CVSS
- 7.5 HIGH
- EPSS (30-day exploit probability)
- 66.0% · top 1% of all CVEs
- Weakness
- NVD-CWE-Other
- Attack vector
- Network, remotely reachable
- Preconditions
- No privileges and no user interaction
Recommended actions
- 1.Apply updates per vendor instructions.
- 2.Treat as emergency change: patch or isolate internet-facing instances first.
- 3.Review exposure: confirm which instances are reachable from the internet and restrict access until patched.
- 4.Hunt for compromise: review logs for the disclosure window, not just from the patch date.
- 5.Verify offline/immutable backups and segment the affected systems. This flaw is used for ransomware initial access.
Assessment is derived automatically from the live signals above; verify against your own asset inventory.