CVE-2023-21559

Local disclosure of confidential information

Published Jan 10, 2023 · Updated Jan 1, 2025

Improper input validation in Microsoft Windows cryptographic processing allows local users to disclose confidential information. Microsoft has not published the affected cryptographic operation, input path, or validation error that exposes the information. Exploitation requires low-privileged local access, needs no user interaction, and affects confidentiality without reported data modification or service interruption.

CVSS severity5.5
Medium
EPSS probability0.58%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper input validation in Microsoft Windows cryptographic processing allows local users to disclose confidential information. Microsoft has not published the affected cryptographic operation, input path, or validation error that exposes the information. Exploitation requires low-privileged local access, needs no user interaction, and affects confidentiality without reported data modification or service interruption.

The record

CVE
CVE-2023-21559
Published
Jan 10, 2023
Updated
Jan 1, 2025
Vendor
Microsoft
Product
Windows Server 2019
Classifications
CWE-20
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jan 10, 2023CVE publishedPublication date reported by the CVE source.
  2. Jan 1, 2025Record 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=10.0.17763.0 <10.0.17763.3887

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Microsoft · Windows Server 2019version=10.0.17763.0 <10.0.17763.3887
Microsoft · Windows 11 version 21H2version=10.0.0 <10.0.22000.1455
Microsoft · Windows 10 Version 21H2version=10.0.19043.0 <10.0.19044.2486
Microsoft · Windows 10 Version 20H2version=10.0.0 <10.0.19042.2486
Microsoft · Windows 10 Version 22H2version=10.0.19045.0 <10.0.19045.2486
Microsoft · Windows Server 2019 (Server Core installation)version=10.0.17763.0 <10.0.17763.3887
Microsoft · Windows 11, version 22H2version=10.0.22621.0 <10.0.22621.1105
Microsoft · Windows Server 2022version=10.0.20348.0 <10.0.20348.1487
Microsoft · Windows 10 Version 1809version=10.0.0 <10.0.17763.3887; version=10.0.17763.0 <10.0.17763.3887

Published CVSS scores

5.5Microsoft CorporationCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/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.

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

CWE-20Improper Input Validation

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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