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CVE-2021-31956

Microsoft Windows NTFS Privilege Escalation

7.8 HIGHActively exploited (CISA KEV)EPSS 22.3%
  1. Published8 Jun 2021
  2. Added to CISA KEV3 Nov 2021
  3. Remediation due17 Nov 2021
Actively exploited (CISA KEV)

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

Added to KEV: 3 Nov 2021Federal remediation due: 17 Nov 2021

Description

Windows NTFS Elevation of Privilege Vulnerability

CVSS 3.1 breakdown

Attack vectorLocal
Attack complexityLow
Privileges requiredLow
User interactionNone
ScopeUnchanged
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

Microsoft Windows 10 1507< 10.0.10240.18967
Microsoft Windows 10 1607< 10.0.14393.4467
Microsoft Windows 10 1809< 10.0.17763.1999
Microsoft Windows 10 1909< 10.0.18363.1621
Microsoft Windows 10 2004< 10.0.19041.1052
Microsoft Windows 10 20h2< 10.0.19042.1052
Microsoft Windows 10 21h1< 10.0.19043.1052
Microsoft Windows 7all versions
Microsoft Windows 8.1all versions
Microsoft Windows Rt 8.1all versions
Microsoft Windows Server 2004< 10.0.19041.1052
Microsoft Windows Server 2008r2 · sp2
Microsoft Windows Server 2012r2
Microsoft Windows Server 2016< 10.0.14393.4467
Microsoft Windows Server 2019< 10.0.17763.1999
Microsoft Windows Server 20h2< 10.0.19042.1052

Remediation

Fixed in
Microsoft Windows 10 1507≥ 10.0.10240.18967
Microsoft Windows 10 1607≥ 10.0.14393.4467
Microsoft Windows 10 1809≥ 10.0.17763.1999
Microsoft Windows 10 1909≥ 10.0.18363.1621
Microsoft Windows 10 2004≥ 10.0.19041.1052
Microsoft Windows 10 20h2≥ 10.0.19042.1052
Microsoft Windows 10 21h1≥ 10.0.19043.1052
Microsoft Windows Server 2004≥ 10.0.19041.1052
Microsoft Windows Server 2016≥ 10.0.14393.4467
Microsoft Windows Server 2019≥ 10.0.17763.1999

References

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Frequently asked

Is CVE-2021-31956 being actively exploited?

Yes. CVE-2021-31956 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, added 3 Nov 2021.

How severe is CVE-2021-31956?

CVE-2021-31956 has a CVSS 3.1 base score of 7.8, rated high. EPSS estimates a 22.3% probability of exploitation.

Which products are affected by CVE-2021-31956?

Affected products include Microsoft Windows 10 1507, Microsoft Windows 10 1607, Microsoft Windows 10 1809, Microsoft Windows 10 1909, Microsoft Windows 10 2004, and 11 more.

How do I fix CVE-2021-31956?

Upgrade affected software to a fixed version, for example Microsoft Windows 10 1507 10.0.10240.18967, Microsoft Windows 10 1607 10.0.14393.4467, Microsoft Windows 10 1809 10.0.17763.1999 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2021-31956 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. Because it is on the CISA KEV list, Secuno flags any affected asset as top-priority automatically. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.