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VulnerabilityCVE-2021-36942Published 2021-08-12

CVE-2021-36942 — Microsoft Windows Server 2004

highCISA KEVRansomware

As of 2025-10-30, CVE-2021-36942 is a HIGH-severity vulnerability in Microsoft Windows Server 2004, CVSS v3.1 7.5, EPSS 93.7% (99.8th percentile). It is listed in the CISA Known Exploited Vulnerabilities catalog (added 2021-11-03), with a US federal remediation deadline of 2021-11-17, and CISA links it to known ransomware campaigns. No Threadlinqs-tracked threat campaign has been attributed to CVE-2021-36942 as of 2025-10-30; the identifier is re-checked against the Threadlinqs threat corpus on every daily ingest.

CVSS v3.1
7.5/10High
EPSS
93.7%Higher than 99.8% of scored CVEs
CISA KEV
ListedAdded · due 2021-11-17
Tracked threats
0None linked yet
Priority
10/10Threadlinqs triage score
Published
Updated 2025-10-30
CVSS v3.1 7.5 (HIGH) · EPSS 93.7% (higher than 99.8% of all scored CVEs) · Priority 10/10 · Published 2021-08-12

Last updated:

What is CVE-2021-36942?

Windows LSA Spoofing Vulnerability

The record classifies CVE-2021-36942 under weakness class NVD-CWE-Other. Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs no user interaction, and has high impact on confidentiality. 8 affected-product entries are recorded, across 1 vendor, listed below. The identifier was first published 1880 days ago.

Severity and exploitation probability

CVSS v3.1 base score
7.5 — HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
EPSS (FIRST)
93.7% probability of exploitation in the next 30 days, higher than 99.8% of all scored CVEs
CISA KEV
Listed since 2021-11-03, federal remediation deadline 2021-11-17 — used in known ransomware campaigns
Threadlinqs priority
10/10 — CISA lists it as used in ransomware, which Threadlinqs scores at the maximum
Published
2021-08-12, last modified 2025-10-30

Is CVE-2021-36942 being exploited?

CISA added CVE-2021-36942 to the Known Exploited Vulnerabilities catalog on 2021-11-03, which means the agency holds evidence of exploitation in the wild; US federal civilian agencies had to remediate it by 2021-11-17 under BOD 22-01. CISA flags the vulnerability as one used in known ransomware campaigns. It currently carries a trending score of 45 in the Threadlinqs vulnerability feed.

Affected products and versions

  • Microsoft: Windows Server 2004, Windows Server 2008, Windows Server 2008 r2, Windows Server 2012, Windows Server 2012 r2, Windows Server 2016, Windows Server 2019, Windows Server 20h2

How to fix CVE-2021-36942

The record marks a vendor fix as available for CVE-2021-36942. Patch reference: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-36942. Vendor advisory: https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-36942. Because CVE-2021-36942 is KEV-listed, US federal civilian agencies were required to apply the vendor fix, or stop using the product, by 2021-11-17. Apply the vendor fix referenced above to every affected product listed in this record, then confirm the running version against the vendor advisory.

Threat activity tracking CVE-2021-36942

No threat campaign in the Threadlinqs corpus currently references CVE-2021-36942, in its CVE list or as an indicator. The linkage is recomputed from the live corpus on every daily ingest, so this section fills in as soon as a tracked campaign cites the identifier.

Sources

Seeded from nvd and not yet processed by the Threadlinqs enrichment pipeline, so blank CVSS, EPSS or KEV fields above mean NOT MEASURED rather than measured-absent.