CVE-2021-26432Network attack vector

Unauthenticated remote code execution

Published Aug 12, 2021 · Updated Aug 10, 2026

Remote code execution in the ONCRPC XDR driver in Microsoft Windows allows remote attackers to execute code through NFS requests. Microsoft identifies the affected locus only as the Windows Services for NFS ONCRPC XDR driver and has not disclosed the specific unsafe operation on request data. Exploitation requires network reachability to Services for NFS, needs no authentication or user interaction, and grants code execution on the target.

CVSS severity9.8
Critical
EPSS probability11.34%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Remote code execution in the ONCRPC XDR driver in Microsoft Windows allows remote attackers to execute code through NFS requests. Microsoft identifies the affected locus only as the Windows Services for NFS ONCRPC XDR driver and has not disclosed the specific unsafe operation on request data. Exploitation requires network reachability to Services for NFS, needs no authentication or user interaction, and grants code execution on the target.

The record

CVE
CVE-2021-26432
Published
Aug 12, 2021
Updated
Aug 10, 2026
Vendor
Microsoft
Product
Windows 10 Version 1507
Classifications
T1210
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 12, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 10, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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

  1. Affected versionversion=10.0.10240.0 <10.0.10240.19022

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Microsoft · Windows 10 Version 1507version=10.0.10240.0 <10.0.10240.19022
Microsoft · Windows Server 2019version=10.0.17763.0 <10.0.17763.2114
Microsoft · Windows 10 Version 21H1version=10.0.0 <10.0.19043.1165
Microsoft · Windows 10 Version 1909version=10.0.0 <10.0.18363.1734
Microsoft · Windows 8.1version=6.3.0 <6.3.9600.20094
Microsoft · Windows Server 2016 (Server Core installation)version=10.0.14393.0 <10.0.14393.4583
Microsoft · Windows Server 2012 (Server Core installation)version=6.2.9200.0 <6.2.9200.23435
Microsoft · Windows Server 2012version=6.2.9200.0 <6.2.9200.23435
Microsoft · Windows Server, version 2004version=10.0.0 <10.0.19041.1165
Microsoft · Windows Server 2016version=10.0.14393.0 <10.0.14393.4583
Microsoft · Windows 10 Version 20H2version=10.0.0 <10.0.19042.1165
Microsoft · Windows Server 2012 R2 (Server Core installation)version=6.3.9600.0 <6.3.9600.20094
Microsoft · Windows Server 2019 (Server Core installation)version=10.0.17763.0 <10.0.17763.2114
Microsoft · Windows Server version 20H2version=10.0.0 <10.0.19042.1165
Microsoft · Windows 10 Version 1607version=10.0.14393.0 <10.0.14393.4583
Microsoft · Windows 10 Version 2004version=10.0.0 <10.0.19041.1165
Microsoft · Windows 10 Version 1809version=10.0.0 <10.0.17763.2114; version=10.0.17763.0 <10.0.17763.2114
Microsoft · Windows Server 2012 R2version=6.3.9600.0 <6.3.9600.20094

Published CVSS scores

9.8MicrosoftCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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

T1210Exploitation of Remote Services

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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