Integer underflow in Microsoft Windows and Windows Server - CVE-2026-83578

Vulnerability identifier: #VU154769

CSH Severity: High

CVSS v4: 9.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-83578

CWE-ID: CWE-191

Exploitation vector: Remote access

Exploit availability: No public exploit available

The vulnerability allows a remote attacker to execute arbitrary code.

The vulnerability exists due to integer underflow in Windows PowerShell when processing network packets. A remote attacker can send a specially crafted packet to an affected service over the network to execute arbitrary code.

No user interaction is required.

Microsoft Windows
Windows Server

Install security update from vendor's website.

Microsoft Windows - addressed in versions 10 21H2 10.0.19044.7807, 10 1607 10.0.14393.9612, 10 1809 10.0.17763.9376, 11 23H2 10.0.22631.7652, 11 24H2 10.0.26100.9711, 11 25H2 10.0.26200.9711, 11 26H1 10.0.28000.3231
Windows Server - addressed in versions 2012 R2 6.3.9600.23470, 2012 6.2.9200.26434, 2016 10.0.14393.9612, 2019 10.0.17763.9376, 2022 10.0.20348.5761, 2025 10.0.26100.33650

• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2026-83578

• Multiple vulnerabilities in Microsoft Windows