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CVE-2025-53809VulnerabilityPublished Updated

CVE-2025-53809: Microsoft Windows 11 Version 24H2 · Improper Input Validation

Affects Microsoft Windows 11 Version 24H2Source CVE Database V5

0

Not known to be exploited · CVSS 6.5 Medium.

Data as of 26 Oct 2026, 06:26 UTC

CVSS 3.1 base score
6.5Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
1.5% chance of exploitation in 30 days – higher than 75% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 9 Sep 2025

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-26.

What to do

Affected software

ProductAffectedFixed in
Microsoft Windows 11 Version 24H2Affected
  • =10.0.26100.0
Fixed in–

AI-suggested

1. Monitor Microsoft security advisories closely and apply official patches or updates as soon as they become available to remediate the vulnerability. 2. Restrict network access to LSASS-related services and ports using network segmentation, firewalls, and access control lists to limit exposure to authorized users only. 3. Implement strict privilege management to ensure that only trusted and necessary accounts have network access privileges that could exploit this vulnerability. 4. Employ network intrusion detection and prevention systems (IDS/IPS) to monitor for anomalous traffic patterns targeting LSASS or related authentication services. 5. Conduct regular system and security audits to detect unusual service crashes or authentication failures that could indicate exploitation attempts. 6. Consider deploying endpoint detection and response (EDR) solutions capable of identifying and alerting on LSASS service disruptions or suspicious activity. 7. Educate IT and security teams about this vulnerability to ensure rapid response and incident handling if exploitation is suspected. 8. In environments where patching may be delayed, consider temporary workarounds such as isolating vulnerable systems from untrusted networks or disabling unnecessary network services that interact with LSASS.

Description

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

References

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