This vulnerability (CVE-2026-26143) in Microsoft PowerShell 7.4 is caused by improper input validation, which enables a local attacker without privileges to bypass a security feature. The CVSS 3.1 score is 7.8, indicating high severity with high impact on confidentiality, integrity, and availability. The vulnerability requires local access and user interaction but has low attack complexity and no privileges required. Microsoft has published an official fix for this issue.

Successful exploitation allows an unauthorized local attacker to bypass security controls, potentially leading to full compromise of confidentiality, integrity, and availability of the affected system. The vulnerability impacts PowerShell 7.4.0 and could be leveraged to escalate privileges or execute unauthorized commands locally.

An official fix is available from Microsoft. Users should apply the security update provided in the Microsoft advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-26143 to remediate this vulnerability.