CVE-2021-31974Network attack vector

Unauthenticated service interruption via undisclosed NFS flaw

Published Jun 8, 2021 · Updated Aug 3, 2024

Denial of service in Server for NFS in Microsoft Windows allows remote attackers to interrupt the service through network requests. Microsoft has not disclosed the vulnerable code path or the operation performed on crafted NFS input. Exploitation requires no authentication or user interaction and affects availability only; the published record does not distinguish a crash from a hang.

CVSS severity7.5
High
EPSS probability6.73%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Server for NFS in Microsoft Windows allows remote attackers to interrupt the service through network requests. Microsoft has not disclosed the vulnerable code path or the operation performed on crafted NFS input. Exploitation requires no authentication or user interaction and affects availability only; the published record does not distinguish a crash from a hang.

The record

CVE
CVE-2021-31974
Published
Jun 8, 2021
Updated
Aug 3, 2024
Vendor
Microsoft
Product
Windows 10 Version 1507
Classifications
T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 8, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=10.0.0 <10.0.10240.18967

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Microsoft · Windows 10 Version 1507version=10.0.0 <10.0.10240.18967
Microsoft · Windows Server 2019version=10.0.0 <10.0.17763.1999
Microsoft · Windows 10 Version 21H1version=10.0.0 <10.0.19043.1052
Microsoft · Windows 10 Version 1909version=10.0.0 <10.0.18363.1621
Microsoft · Windows 8.1version=6.3.0 <6.3.9600.20044; version=6.3.0 <6.3.9600.20045
Microsoft · Windows Server 2016 (Server Core installation)version=10.0.0 <10.0.14393.4467
Microsoft · Windows Server 2012 (Server Core installation)version=6.2.0 <6.2.9200.23372
Microsoft · Windows Server 2012version=6.2.0 <6.2.9200.23372
Microsoft · Windows Server, version 2004version=10.0.0 <10.0.19041.1052
Microsoft · Windows Server 2016version=10.0.0 <10.0.14393.4467
Microsoft · Windows 10 Version 20H2version=10.0.0 <10.0.19042.1052
Microsoft · Windows Server 2012 R2 (Server Core installation)version=6.3.0 <6.3.9600.20044; version=6.3.0 <6.3.9600.20045
Microsoft · Windows Server 2019 (Server Core installation)version=10.0.0 <10.0.17763.1999
Microsoft · Windows Server version 20H2version=10.0.0 <10.0.19042.1052
Microsoft · Windows 10 Version 1607version=10.0.0 <10.0.14393.4467
Microsoft · Windows 10 Version 2004version=10.0.0 <10.0.19041.1052
Microsoft · Windows 10 Version 1809version=10.0.0 <10.0.17763.1999
Microsoft · Windows Server 2012 R2version=6.3.0 <6.3.9600.20044; version=6.3.0 <6.3.9600.20045

Published CVSS scores

5.0NIST NVDAV:N/AC:L/Au:N/C:N/I:N/A:P
7.5Microsoft CorporationCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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