Cyber Resilience

CVE-2021-36942

HighCISA KEVActive ExploitationEUVD ExploitedPublic PoCRansomware-linked

Published: 12 August 2021

Published
12 August 2021
Modified
30 October 2025
KEV Added
03 November 2021
Patch
CVSS Score v3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
EPSS Score 0.9355 99.8th percentile
Risk Priority 91 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2021-36942 is a high-severity an unspecified weakness vulnerability in Microsoft Windows Server 2008. Its CVSS base score is 7.5 (High).

Operationally, ranked in the top 0.2% of CVEs by exploit likelihood; CISA has added it to the Known Exploited Vulnerabilities catalog; a public proof-of-concept is referenced.

The strongest mitigations our analysis identified are NIST 800-53 AC-4 (Information Flow Enforcement) and SC-8 (Transmission Confidentiality and Integrity).

Deeper analysis

CVE-2021-36942 is a spoofing vulnerability affecting the Local Security Authority (LSA) component in Windows. It carries a CVSS 3.1 base score of 7.5 with a vector indicating network attack vector, low attack complexity, no required privileges or user interaction, and high impact to confidentiality.

An unauthenticated attacker can exploit the flaw remotely to spoof LSA communications and obtain sensitive information from the affected system.

Microsoft security advisories and related CERT coordination guidance address mitigation steps, while the vulnerability appears in CISA's catalog of known exploited vulnerabilities in the wild.

EU & UK References

Vulnerability details

Windows LSA Spoofing Vulnerability

CWE(s)
KEV Date Added
03 November 2021

Related Threats

No named actor attribution yet. ATT&CK technique mapping in progress for this CVE.

Affected Assets

microsoft
windows server 2004
≤ 10.0.19041.1165
microsoft
windows server 2008
all versions, r2
microsoft
windows server 2012
all versions, r2
microsoft
windows server 2016
≤ 10.0.14393.4583
microsoft
windows server 2019
≤ 10.0.17763.2114
microsoft
windows server 20h2
≤ 10.0.19042.1165

Mitigating Controls

Mitigating Controls (NIST 800-53 r5) AI

prevent

Directly enforces information flow policies on LSA communications, blocking the unauthenticated spoofing that enables remote disclosure.

prevent

Requires cryptographic integrity protection for LSA network transmissions, directly stopping spoofing of LSA messages.

prevent

Mandates identification and authentication of services such as LSA before allowing communications, mitigating the unauthenticated remote spoof.

References