CVE-2025-53809Network attack vector

Authenticated service interruption via invalid network input

Published Sep 9, 2025 · Updated Sep 9, 2025

Improper input validation in Windows LSASS allows remote authenticated users to interrupt service through network input. Microsoft has not disclosed the specific input, parsing path, or invalid operation inside LSASS that triggers the condition. Low-privileged network access is sufficient, and the documented consequence is limited to availability without data disclosure or modification.

CVSS severity6.5
Medium
EPSS probability1.47%
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 Windows LSASS allows remote authenticated users to interrupt service through network input. Microsoft has not disclosed the specific input, parsing path, or invalid operation inside LSASS that triggers the condition. Low-privileged network access is sufficient, and the documented consequence is limited to availability without data disclosure or modification.

The record

CVE
CVE-2025-53809
Published
Sep 9, 2025
Updated
Sep 9, 2025
Vendor
Microsoft
Product
Windows Server 2025 (Server Core installation)
Classifications
CWE-20, T1499
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 9, 2025CVE publishedPublication date reported by the CVE source.
  2. Sep 9, 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=10.0.26100.0 <10.0.26100.6584

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Microsoft · Windows Server 2025 (Server Core installation)version=10.0.26100.0 <10.0.26100.6584
Microsoft · Windows 11, version 24H2version=10.0.26100.0 <10.0.26100.6584
Microsoft · Windows Server 2025version=10.0.26100.0 <10.0.26100.6584

Published CVSS scores

6.5MicrosoftCVSS:3.1/AV:N/AC:L/PR:L/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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
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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