CVE-2021-40455

Local data alteration via undisclosed installer flaw

Published Oct 13, 2021 · Updated Aug 4, 2024

Windows Installer spoofing in affected Microsoft Windows releases allows local users to alter protected data via unspecified vectors. Microsoft has not published the affected Installer locus or the operation that mishandles attacker-controlled input. Exploitation requires local low-privilege access and grants an integrity impact without reported data disclosure or service interruption.

CVSS severity5.5
Medium
EPSS probability0.56%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Windows Installer spoofing in affected Microsoft Windows releases allows local users to alter protected data via unspecified vectors. Microsoft has not published the affected Installer locus or the operation that mishandles attacker-controlled input. Exploitation requires local low-privilege access and grants an integrity impact without reported data disclosure or service interruption.

The record

CVE
CVE-2021-40455
Published
Oct 13, 2021
Updated
Aug 4, 2024
Vendor
Microsoft
Product
Windows 10 Version 1507
Classifications
Unavailable
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Oct 13, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 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 <10.0.10240.19086

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Microsoft · Windows 10 Version 1507version=10.0.0 <10.0.10240.19086
Microsoft · Windows Server 2019version=10.0.0 <10.0.17763.2237
Microsoft · Windows 7version=6.1.0 <6.1.7601.25740
Microsoft · Windows 10 Version 21H1version=10.0.0 <10.0.19041.1288
Microsoft · Windows 10 Version 1909version=10.0.0 <10.0.18363.1854
Microsoft · Windows 8.1version=6.3.0 <6.3.9600.20144
Microsoft · Windows Server 2016 (Server Core installation)version=10.0.0 <10.0.14393.4704
Microsoft · Windows 11 version 21H2version=10.0.0 <10.0.22000.258
Microsoft · Windows Server 2012 (Server Core installation)version=6.2.0 <6.2.9200.23490
Microsoft · Windows Server 2012version=6.2.0 <6.2.9200.23490
Microsoft · Windows Server, version 2004version=10.0.0 <10.0.19041.1288
Microsoft · Windows Server 2016version=10.0.0 <10.0.14393.4704
Microsoft · Windows Server 2008 R2 Service Pack 1version=6.1.0 <6.1.7601.25740
Microsoft · Windows 10 Version 20H2version=10.0.0 <10.0.19041.1288
Microsoft · Windows Server 2008 R2 Service Pack 1 (Server Core installation)version=6.0.0 <6.1.7601.25740
Microsoft · Windows Server 2012 R2 (Server Core installation)version=6.3.0 <6.3.9600.20144
Microsoft · Windows Server 2019 (Server Core installation)version=10.0.0 <10.0.17763.2237
Microsoft · Windows 7 Service Pack 1version=6.1.0 <6.1.7601.25740
Microsoft · Windows Server version 20H2version=10.0.0 <10.0.19042.1288
Microsoft · Windows 10 Version 1607version=10.0.0 <10.0.14393.4704
Microsoft · Windows Server 2008 Service Pack 2version=6.0.0 <6.0.6003.21251
Microsoft · Windows Server 2022version=10.0.0 <10.0.20348.288
Microsoft · Windows 10 Version 2004version=10.0.0 <10.0.19041.1288
Microsoft · Windows 10 Version 1809version=10.0.0 <10.0.17763.2237
Microsoft · Windows Server 2012 R2version=6.3.0 <6.3.9600.20144
Microsoft · Windows Server 2008 Service Pack 2 (Server Core installation)version=6.0.0 <6.0.6003.21251

Published CVSS scores

2.1NIST NVDAV:L/AC:L/Au:N/C:N/I:P/A:N
5.5Microsoft CorporationCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/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.

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)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

No sourced classifications are available.

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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