CVE-2026-85790: Use after free in Microsoft QUIC allows an unauthorized attacker to disclose information over a network.

CVE-2026-85790 · Severity: medium · CVSS 5.9 · Published 2026-10-13

A vulnerability in the QUIC networking component of Microsoft .NET can leak sensitive information to remote attackers without authentication. The flaw exists in the native MsQuic library used for encrypted network communication and could expose data transmitted or processed by affected .NET applications.

Technologies: Microsoft .Net, Microsoft Visual Studio 2022, Microsoft Visual Studio 2026, Microsoft Windows 11 23h2, Microsoft Windows 11 24h2, Microsoft Windows 11 25h2, Microsoft Windows 11 26h1, Microsoft Windows 11 26h2, Microsoft Windows Server 2022, Microsoft Windows Server 2025, Microsoft.Native.Quic.MsQuic.Schannel (NuGet). Vendors: Microsoft, NuGet.

Quick answers

Is CVE-2026-85790 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-85790 being exploited in the wild.
How severe is CVE-2026-85790?
Medium severity, with a CVSS score of 5.9, published 13 October 2026.
Which products and versions are affected?
Microsoft .Net Microsoft.Native.Quic.MsQuic.Schannel 1.9.0 through 2.6.1; Microsoft.Native.Quic.MsQuic.Schannel (NuGet) >= 1.9.0, <= 2.6.1, ECOSYSTEM:introduced=1.9.0,fixed=2.6.2.
Is there a fix for CVE-2026-85790?
Yes. Microsoft.Native.Quic.MsQuic.Schannel (NuGet): upgrade to 2.6.2 or later. Until then: Update the Microsoft.Native.Quic.MsQuic.Schannel package reference to version 2.6.2 or later; self-contained applications targeting affected versions must be recompiled and redeployed.</anigation> <parameter name="timeline">[{"kind": "disclosed", "at": "2026-10-13"}, {"kind": "advisory", "at": "2026-10-13"}] Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-85790 attacked?
It is attacked over the network, in a software library.
Am I affected by CVE-2026-85790?
Check whether you run Microsoft .Net, Microsoft Native.Quic.Msquic.Schannel, Microsoft Visual Studio 2022 or one of the others listed at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • Microsoft.Native.Quic.MsQuic.Schannel (NuGet): upgrade to 2.6.2 or later
    dotnet add package Microsoft.Native.Quic.MsQuic.Schannel --version 2.6.2

Update the Microsoft.Native.Quic.MsQuic.Schannel package reference to version 2.6.2 or later; self-contained applications targeting affected versions must be recompiled and redeployed.</anigation> <parameter name="timeline">[{"kind": "disclosed", "at": "2026-10-13"}, {"kind": "advisory", "at": "2026-10-13"}]

Technical details

A use-after-free vulnerability in Microsoft.Native.Quic.MsQuic.Schannel's Schannel provider permits information disclosure via network access without authentication or user interaction. The attack requires specific conditions (high complexity) but allows an unauthenticated remote attacker to read sensitive data. A fix is available in patched versions.

Affected products

  • Microsoft .NET Microsoft.Native.Quic.MsQuic.Schannel 1.9.0 through 2.6.1

Identifiers

  • CVE-2026-85790
  • GHSA-2mxg-prvg-9jfg

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