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VulnerabilityPublished Updated

CVE-2026-40405: Microsoft Windows 11 Version 24H2 · NULL Pointer Dereference

Affects Microsoft Windows 11 Version 24H2Source CVE Database V5

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Not known to be exploited · CVSS 7.5 High : upgrade to 10.0.26100.8457 soon.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 3.1 base score
7.5High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
1.0% chance of exploitation in 30 days – higher than 64% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 10.0.26100.8457, 10.0.26200.8457, 10.0.28000.2113 +1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 12 May 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: 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 30 Oct 2026.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

ProductAffectedFixed in
MicrosoftWindows 11 Version 24H2Affected
  • >=10.0.26100.0 <10.0.26100.8457
Fixed in
  • 10.0.26100.8457
MicrosoftWindows 11 Version 25H2Affected
  • >=10.0.26200.0 <10.0.26200.8457
Fixed in
  • 10.0.26200.8457
MicrosoftWindows 11 version 26H1Affected
  • >=10.0.28000.0 <10.0.28000.2113
Fixed in
  • 10.0.28000.2113
MicrosoftWindows Server 2025Affected
  • >=10.0.26100.0 <10.0.26100.32860
Fixed in
  • 10.0.26100.32860
MicrosoftWindows Server 2025 (Server Core installation)Affected
  • >=10.0.26100.0 <10.0.26100.32860
Fixed in
  • 10.0.26100.32860

AI-suggested

An official fix is available from Microsoft. Users and administrators should apply the security update provided in the Microsoft advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-40405 to remediate this vulnerability.

Description

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

References

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