Is CVE-2021-31956 in the CISA KEV catalog?

Yes. CVE-2021-31956 is on the CISA Known Exploited Vulnerabilities list, added 2021-11-03.

What is the CVSS severity of CVE-2021-31956?

CVE-2021-31956 has a CVSS v3 base score of 7.8 (HIGH).

What is the EPSS score for CVE-2021-31956?

CVE-2021-31956 has an EPSS score of 20.27% (97th percentile), estimating the probability of exploitation in the next 30 days.

CVE & CISA-KEV Catalog

CVE-2021-31956

HIGHCISA KEVEPSS 97th pctl

7.8

CVSS v3

NVD

Description

Windows NTFS Elevation of Privilege Vulnerability

CWE-191

CVSS v3 Vector

Exploitability

Attack VectorLocal

Attack ComplexityLow

Privileges RequiredLow

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Exploit Intelligence

20.27%probability of exploitation in 30 days

97thpercentile

Very high risk: more likely to be exploited than 97% of all known CVEs.

Known Exploited Vulnerability (CISA KEV)

Microsoft Windows NTFS Privilege Escalation Vulnerability

Microsoft Windows New Technology File System (NTFS) contains an unspecified vulnerability that allows attackers to escalate privileges via a specially crafted application.

Apply updates per vendor instructions.

Remediation due: 2021-11-17

References

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-01-13.