CVE-2026-62815: Microsoft QUIC Remote Code Execution Vulnerability

Overview

Severity

Critical (CVSS 9.8)

CVSS Vector

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

Category

Remote Code Execution

Exploit Status

Not Exploited

Patch Tuesday

2026-Aug

Released

2026-08-11

Description

Use after free in Microsoft QUIC allows an unauthorized attacker to execute code over a network.

FAQ

How could an attacker exploit this vulnerability? An unauthenticated attacker could exploit this vulnerability by sending a specially crafted packet to an affected service over the network. Successful exploitation could allow the attacker to execute code on the target system. No authentication or user interaction is required.

Affected Products (12)

Windows

• Windows Server 2022
• Windows Server 2022 (Server Core installation)
• 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

Security Updates (8)

• 5120242
• 5120229
• 5120233
• 5120228
• 5121003
• 5120994
• 5120240
• 5121000

Acknowledgments

pwn2addr, <a href="https://twitter.com/guhe120">AIフィジカルインターフェイス二号機</a>

Revision History

• 2026-08-11: Information published.