CVE-2025-53809

Name: CVE-2025-53809
Creator: NVD / NIST
Published: 2025-09-09T17:15:52.163+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.5/10EPSS 1.37%

Last modified Jun 17, 2026

CVE-2025-53809 is a medium-severity vulnerability rated 6.5/10 on the CVSS scale. Improper input validation in Windows Local Security Authority Subsystem Service (LSASS) allows an authorized attacker to deny service over a network.. EPSS estimates a 1.37% chance of exploitation in the next 30 days.

Description

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

Metrics

CVSS 3.1

6.5/10

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

EPSS Probability

1.37%

68.4th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-20

Affected Software

Vendor	Product	Versions
Microsoft	Windows 11 24h2	< 10.0.26100.6508
Microsoft	Windows Server 2025	< 10.0.26100.6508

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-53809Vendor Advisory

Timeline

Published: Sep 9, 2025
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2025-53809?

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

How severe is CVE-2025-53809?

CVE-2025-53809 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 1.37% probability of exploitation in the next 30 days.

How do I fix CVE-2025-53809?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2025-53809?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST