CVE-2026-85790: Microsoft QUIC Information Disclosure Vulnerability

Overview

Severity
Medium (CVSS 5.9)
CVSS Vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N/E:U/RL:O/RC:C
Category
Information Disclosure
Exploit Status
Not Exploited
Exploitation Likelihood
Less Likely
Patch Tuesday
2026-Oct
Released
2026-10-13

Description

Use after free in Microsoft QUIC allows an unauthorized attacker to disclose information over a network.

FAQ

According to the CVSS metric, the attack complexity is high (AC:H). What does that mean for this vulnerability? Successful exploitation of this vulnerability requires an attacker to have a deep understanding of the system. Successful exploitation is not guaranteed and depends on a combination of factors that might include the environment, system configuration, and the presence of additional security measures. What type of information could be disclosed by this vulnerability? An attacker who successfully exploited this vulnerability could view heap memory from a privileged process running on the server.

Affected Products (20)

Windows

  • Windows 11 Version 26H2 for ARM64-based Systems
  • Windows 11 Version 26H2 for x64-based Systems
  • 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

Developer Tools

  • Microsoft Visual Studio 2026 version 18.10
  • Microsoft Visual Studio 2022 version 17.14

Other

  • Microsoft.Native.Quic.MsQuic.Schannel on .NET 10.0 installed on Windows
  • Microsoft.Native.Quic.MsQuic.Schannel on .NET 11.0 installed on Windows
  • Microsoft.Native.Quic.MsQuic.Schannel on .NET 8.0 installed on Windows
  • Microsoft.Native.Quic.MsQuic.Schannel on .NET 9.0 installed on Windows

Security Updates (6)

Acknowledgments

reinusKR, reinusKR

Revision History

  • 2026-10-13: Information published.