CVE-2025-59257

Windows Local Session Manager (LSM) Denial of Service Vulnerability

CVE-2025-59257 is fixed in 7 products on 1 platform, first by KB5066835, released October 14, 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

0.0154

75th percentile

<p>Improper validation of specified type of input in Windows Local Session Manager (LSM) 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		KB5066835	Oct 14, 2025
Windows 11 Version 24H2 for x64-based Systems		KB5066835	Oct 14, 2025
Windows 11 Version 25H2 for ARM64-based Systems		KB5066835	Oct 14, 2025
Windows 11 Version 25H2 for x64-based Systems		KB5066835	Oct 14, 2025
Windows Server 2022, 23H2 Edition (Server Core installation)	25398.1913	KB5066780	Oct 14, 2025
Windows Server 2025		KB5066835	Oct 14, 2025
Windows Server 2025 (Server Core installation)		KB5066835	Oct 14, 2025

Details

Published
October 14, 2025
Weakness
Improper Validation of Specified Type of Input
Vendor advisory
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-59257

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