CVE-2026-83845: Windows Internet (wininet.dll) Spoofing Vulnerability

Overview

Severity

High (CVSS 8.4)

CVSS Vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N/E:U/RL:O/RC:C

Category

Spoofing

Exploit Status

Not Exploited

Exploitation Likelihood

Less Likely

Patch Tuesday

2026-Oct

Released

2026-10-13

Description

Improper privilege management in Windows Internet (wininet.dll) allows an authorized attacker to perform spoofing locally.

FAQ

How could an attacker exploit this vulnerability? An attacker running code in a low-integrity AppContainer could send a local request that claims the identity of another package belonging to the same user. Successful exploitation could allow the attacker to read or modify the other package's cookies. No additional user interaction is required.

Affected Products (20)

Windows

• Windows Server 2022
• Windows Server 2022 (Server Core installation)
• Windows 10 Version 21H2 for 32-bit Systems
• Windows 10 Version 21H2 for ARM64-based Systems
• Windows 10 Version 21H2 for x64-based Systems
• Windows Server 2025 (Server Core installation)
• Windows 11 Version 25H2 for ARM64-based Systems
• Windows 11 Version 25H2 for x64-based Systems
• Windows 11 Version 23H2 for ARM64-based Systems
• Windows 11 Version 23H2 for x64-based Systems
• Windows 11 Version 24H2 for ARM64-based Systems
• Windows 11 Version 24H2 for x64-based Systems
• Windows Server 2025
• Windows 11 version 26H1 for x64-based Systems
• Windows 11 Version 26H1 for ARM64-based Systems
• Windows 11 Version 26H2 for ARM64-based Systems
• Windows 11 Version 26H2 for x64-based Systems

ESU

• Windows 10 Version 22H2 for x64-based Systems
• Windows 10 Version 22H2 for ARM64-based Systems
• Windows 10 Version 22H2 for 32-bit Systems

Security Updates (6)

• 5126655
• 5126657
• 5126646
• 5127648
• 5126653
• 5127646

Acknowledgments

haowei yan

Revision History

• 2026-10-13: Information published.