CVE-2025-53809

Local Security Authority Subsystem Service (LSASS) Denial of Service Vulnerability

CVE-2025-53809 is fixed in 4 products on 1 platform, first by KB5065426, released September 9, 2025. It is not reported as exploited. Patch Radar priority: Routine.

Routine

CVSS

6.5

Important

Exploitation

None reported

Exploitation Less Likely

CISA KEV

Not listed

Not in the Known Exploited Vulnerabilities catalog

EPSS

0.0157

75th percentile

<p>Improper input validation in Windows Local Security Authority Subsystem Service (LSASS) allows an authorized attacker to deny service over a network.</p>

Where it's fixed

Product	Fixed in	Fix	Released
Microsoft
Windows 11 Version 24H2 for ARM64-based Systems	26100.6584	KB5065426	Sep 9, 2025
Windows 11 Version 24H2 for ARM64-based Systems	26100.6508	KB5065474	Sep 9, 2025
Windows 11 Version 24H2 for x64-based Systems	26100.6584	KB5065426	Sep 9, 2025
Windows 11 Version 24H2 for x64-based Systems	26100.6508	KB5065474	Sep 9, 2025
Windows Server 2025	26100.6584	KB5065426	Sep 9, 2025
Windows Server 2025	26100.6508	KB5065474	Sep 9, 2025
Windows Server 2025 (Server Core installation)	26100.6584	KB5065426	Sep 9, 2025
Windows Server 2025 (Server Core installation)	26100.6508	KB5065474	Sep 9, 2025

Details

Published
September 9, 2025
Weakness
Improper Input Validation
Vendor advisory
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-53809

For tools and AI agents

This page as data: JSON · Markdown

Link to this page

If this page saved you time, a link to it in your ticket, advisory or write-up helps others find it.

HTML

<a href="https://patchblox.com/security/cve/CVE-2025-53809">CVE-2025-53809 on Patchblox Patch Radar</a>

Reusing the data? How to credit Patch Radar.

Is this on your machines?

Patchblox finds every install below the fixed version on Windows, macOS and Linux, and updates them through your release rings.

Get a demo

Patch Radar data is free to use with attribution. Terms and how to credit it.

Product names, logos and trademarks shown on Patch Radar belong to their respective owners. They are used only to identify the software each security fix applies to and to help readers find their platform. Their use does not imply any affiliation with, or endorsement by, those owners, and Patchblox is not affiliated with any of them.