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Input Validation Flaw in Microsoft PowerShell Allows Local Privilege Escalation

Last refreshed2026-09-26

Status: UPDATED  |  Advisory ID: CVE-2026-26170

Key Details

CVECVE-2026-26170
CVSS Score / Version7.8 (High) / CVSS v3.1
Updated2026-09-24
CVSS VectorCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CVSS Proseattack vector is local; attack complexity is low; privileges required is low; user interaction is none; scope is unchanged; confidentiality impact is high; integrity impact is high; availability impact is high.
Affected productssee table below
Classified asCWE-20 (Improper Input Validation)
Exploitation prediction (EPSS)0.33% probability of exploitation in the next 30 days (24% percentile) -- FIRST.org's EPSS model.

Affected Products, Subsystems & Sectors

VendorProductAffected VersionsPatch Status
MicrosoftWindows 11 (version 23H2)
MicrosoftWindows 11 (version 24H2)
MicrosoftWindows 11 (version 25H2)
MicrosoftWindows 11 (version 26H1)
MicrosoftWindows Server 2025
MicrosoftWindows 10 (version 1607)
MicrosoftWindows 10 (version 1809)
MicrosoftWindows 10 (version 21H2)
MicrosoftWindows 10 (version 22H2)
MicrosoftWindows Server 2016
MicrosoftWindows Server 2019
MicrosoftWindows Server 2022
MicrosoftWindows Server 2022 (version 23H2)
SubsystemsCore Infrastructure, EWS Workstation Delivery/Virtualization
SectorsAll Sectors

What to Know

Improper input validation in Microsoft PowerShell allows an authorized attacker to elevate privileges locally.

What to Do

Monitor Microsoft's web page for any future patch releases. See vendor advisory link below.

References

SourceReference
NVDhttps://nvd.nist.gov/vuln/detail/CVE-2026-26170
CVEhttps://www.cve.org/CVERecord?id=CVE-2026-26170
Vendor advisoryhttps://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-26170