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Vulnerabilities

Vulnerability · CVE-2026-40405

Null pointer dereference in Windows TCP/IP allows an unauthorized attacker to deny service over a network.

Published May 12, 2026 · catalog updated Jun 17, 2026 · windows 11 24h2

Check if you run it

No confirmed exploitation is on record for CVE-2026-40405. EPSS is 1.17%. Act only if a listed version of windows 11 24h2 is installed.

Gaps on this record

  • No version range is stored. A customer cannot check an installed version against this record.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High7.5
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
1.17%
Remediation
Advisory link
Affected products
cpe microsoft/windows 11 24h2 · cpe microsoft/windows 11 25h2 · cpe microsoft/windows 11 26h1 · cpe microsoft/windows server 2025

Null pointer dereference in Windows TCP/IP allows an unauthorized attacker to deny service over a network.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe microsoft/windows 11 24h2version unspecified
  • cpe microsoft/windows 11 25h2version unspecified
  • cpe microsoft/windows 11 26h1version unspecified
  • cpe microsoft/windows server 2025version unspecified

How to fix CVE-2026-40405

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-40405. EPSS is 1.17%. Act only if a listed version of windows 11 24h2 is installed.

Which versions are affected?

Affected version ranges are not on this record. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-476: NULL Pointer Dereference. EPSS 1.17%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

Windows security

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. May 12, 2026 · NIST NVD

    Detected

    Null pointer dereference in Windows TCP/IP allows an unauthorized attacker to deny service over a network.

  2. Jun 17, 2026 · NIST NVD

    Updated

    Null pointer dereference in Windows TCP/IP allows an unauthorized attacker to deny service over a network.

Sources

  • CVE.orgVulnerability recordCVE-2026-40405

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-40405

    30-day exploitation probability 1.2%

    first.org
  • NIST NVDVulnerability recordCVE-2026-40405

    Null pointer dereference in Windows TCP/IP allows an unauthorized attacker to deny service over a network.

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.