CVE-2021-1678Network attack vector

Client spoofing via weak remote Winspool authentication

Published Jan 12, 2021 · Updated Oct 8, 2024

Authentication bypass in Microsoft Windows Print Spooler allows remote attackers to spoof clients through the remote Winspool RPC interface. The Printer RPC binding accepts remote Winspool traffic without the higher authentication level needed to enforce packet privacy. User interaction is required to initiate the connection, and Microsoft has not published further details about the attacker's post-authentication actions.

CVSS severity8.8
High
EPSS probability9.38%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in Microsoft Windows Print Spooler allows remote attackers to spoof clients through the remote Winspool RPC interface. The Printer RPC binding accepts remote Winspool traffic without the higher authentication level needed to enforce packet privacy. User interaction is required to initiate the connection, and Microsoft has not published further details about the attacker's post-authentication actions.

The record

CVE
CVE-2021-1678
Published
Jan 12, 2021
Updated
Oct 8, 2024
Vendor
Microsoft
Product
Windows 10 Version 1507
Classifications
T1187
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 12, 2021CVE publishedPublication date reported by the CVE source.
  2. Oct 8, 2024Record 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=10.0.0 <10.0.10240.19060

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Microsoft · Windows 10 Version 1507version=10.0.0 <10.0.10240.19060
Microsoft · Windows Server 2019version=10.0.0 <10.0.17763.2183
Microsoft · Windows 7version=6.1.0 <6.1.7601.25712
Microsoft · Windows 10 Version 1909version=10.0.0 <10.0.18363.1801
Microsoft · Windows 10 Version 1803version=10.0.0 <publication
Microsoft · Windows 8.1version=6.3.0 <6.3.9600.20120
Microsoft · Windows Server 2016 (Server Core installation)version=10.0.0 <10.0.14393.4651
Microsoft · Windows Server 2012 (Server Core installation)version=6.2.0 <6.2.9200.23462
Microsoft · Windows Server 2012version=6.2.0 <6.2.9200.23462
Microsoft · Windows Server, version 2004version=10.0.0 <10.0.19041.1237
Microsoft · Windows Server 2016version=10.0.0 <10.0.14393.4651
Microsoft · Windows Server 2008 R2 Service Pack 1version=6.1.0 <6.1.7601.25712
Microsoft · Windows 10 Version 20H2version=10.0.0 <10.0.19041.1237
Microsoft · Windows Server 2008 R2 Service Pack 1 (Server Core installation)version=6.0.0 <6.1.7601.25712
Microsoft · Windows Server 2012 R2 (Server Core installation)version=6.3.0 <6.3.9600.20120
Microsoft · Windows Server 2019 (Server Core installation)version=10.0.0 <10.0.17763.2183
Microsoft · Windows 7 Service Pack 1version=6.1.0 <6.1.7601.25712
Microsoft · Windows Server version 20H2version=10.0.0 <10.0.19041.1237
Microsoft · Windows 10 Version 1607version=10.0.0 <10.0.14393.4651
Microsoft · Windows Server 2008 Service Pack 2version=6.0.0 <6.0.6003.21218
Microsoft · Windows 10 Version 2004version=10.0.0 <10.0.19041.1237
Microsoft · Windows 10 Version 1809version=10.0.0 <10.0.17763.2183
Microsoft · Windows Server 2012 R2version=6.3.0 <6.3.9600.20120
Microsoft · Windows Server 2008 Service Pack 2 (Server Core installation)version=6.0.0 <6.0.6003.21218
Microsoft · Windows Server, version 1909 (Server Core installation)version=10.0.0 <publication

Published CVSS scores

8.8Microsoft CorporationCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
5.0NIST NVDAV:N/AC:L/Au:N/C:P/I:N/A:N

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.

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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

T1187Forced Authentication

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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