CVE-2026-26154Network attack vector

Unauthenticated service interruption via undisclosed input validation

Published Apr 14, 2026 · Updated Apr 14, 2026

Improper input validation in Microsoft WSUS on affected Windows Server releases allows remote attackers to interrupt service over a network. Microsoft has not disclosed the input field, processing locus, or invalid operation that causes the availability impact. The WSUS server role must be present and network-reachable; the published impact is limited to service availability.

CVSS severity7.5
High
EPSS probability1.06%
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 WSUS on affected Windows Server releases allows remote attackers to interrupt service over a network. Microsoft has not disclosed the input field, processing locus, or invalid operation that causes the availability impact. The WSUS server role must be present and network-reachable; the published impact is limited to service availability.

The record

CVE
CVE-2026-26154
Published
Apr 14, 2026
Updated
Apr 14, 2026
Vendor
Microsoft
Product
Windows Server 2019
Classifications
CWE-20, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 14, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 14, 2026Record 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=10.0.17763.0 <10.0.17763.8644

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Microsoft · Windows Server 2019version=10.0.17763.0 <10.0.17763.8644
Microsoft · Windows Server 2025 (Server Core installation)version=10.0.26100.0 <10.0.26100.32690
Microsoft · Windows Server 2016 (Server Core installation)version=10.0.14393.0 <10.0.14393.9060
Microsoft · Windows Server 2012 (Server Core installation)version=6.2.9200.0 <6.2.9200.26026
Microsoft · Windows Server 2012version=6.2.9200.0 <6.2.9200.26026
Microsoft · Windows Server 2022, 23H2 Edition (Server Core installation)version=10.0.25398.0 <10.0.25398.2274
Microsoft · Windows Server 2016version=10.0.14393.0 <10.0.14393.9060
Microsoft · Windows Server 2012 R2 (Server Core installation)version=6.3.9600.0 <6.3.9600.23132
Microsoft · Windows Server 2019 (Server Core installation)version=10.0.17763.0 <10.0.17763.8644
Microsoft · Windows Server 2022version=10.0.20348.0 <10.0.20348.5020
Microsoft · Windows Server 2025version=10.0.26100.0 <10.0.26100.32690
Microsoft · Windows Server 2012 R2version=6.3.9600.0 <6.3.9600.23132

Published CVSS scores

7.5MicrosoftCVSS: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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-20Improper Input Validation
T1499Endpoint Denial of Service

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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