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CVE-2026-40400 Microsoft CVE debrief

A relative path traversal vulnerability in Windows PowerShell allows an authorized attacker to execute code over a network. The vulnerability has a CVSS score of 8 and is classified as HIGH. Microsoft has released a patch for this vulnerability. The vulnerability exists in Windows PowerShell and allows an authorized attacker to execute code over a network. Affected products include various versions of Windows 10, Windows 11, and Windows Server. System administrators and users of Windows PowerShell should be aware of this vulnerability and take necessary precautions to prevent exploitation.

Vendor
Microsoft
Product
Windows 10 Version 1607
CVSS
HIGH 8
CISA KEV
Not listed in stored evidence
Original CVE published
2026-07-14
Original CVE updated
2026-07-22
Advisory published
2026-07-14
Advisory updated
2026-07-22

Who should care

System administrators and users of Windows PowerShell should be aware of this vulnerability and take necessary precautions to prevent exploitation. This includes reviewing the official CVE record and NVD entry for the latest information, applying the patch released by Microsoft, and restricting access to Windows PowerShell.

Technical summary

The vulnerability exists in Windows PowerShell and allows an authorized attacker to execute code over a network. The CVSS vector for this vulnerability is CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H. Affected products include various versions of Windows 10, Windows 11, and Windows Server. The vulnerability has a CVSS score of 8 and is classified as HIGH.

Defensive priority

High

Recommended defensive actions

  • Apply the patch released by Microsoft
  • Restrict access to Windows PowerShell
  • Monitor system logs for suspicious activity
  • Review compensating controls for exposed systems while remediation is scheduled and verified
  • Check relevant monitoring, detection, and logs for exposed assets that need extra review

Evidence notes

The CVE record was published on 2026-07-14T17:16:47.447Z and was last modified on 2026-07-16T19:44:39.227Z. The NVD entry is currently Analyzed. The vulnerability has a CVSS score of 8 and is classified as HIGH. Microsoft has released a patch for this vulnerability. However, details about the patch and affected products are limited. Defenders should verify the official CVE record and NVD entry for the latest information.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-40400 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-40400

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-40400 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-40400

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.