CVE-2026-105016: Heap-based buffer overflow in Microsoft QUIC allows an unauthorized attacker to execute code over a network.

CVE-2026-105016 · Severity: critical · CVSS 9.8 · Published 2026-10-13

Microsoft QUIC, a protocol component used in .NET for secure communications, contains a heap-based buffer overflow vulnerability in its HTTP/3 implementation. An attacker can send a specially crafted IPv6 QUIC packet over the network to trigger remote code execution without requiring any authentication or user interaction, potentially allowing complete compromise of affected systems.

Technologies: Microsoft .Net, Microsoft.Native.Quic.MsQuic.Schannel (NuGet). Vendors: Microsoft, NuGet.

Quick answers

Is CVE-2026-105016 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-105016 being exploited in the wild.
How severe is CVE-2026-105016?
Critical severity, with a CVSS score of 9.8, published 13 October 2026.
Which products and versions are affected?
Microsoft .Net 8.0, 9.0, 10.0, 11 RC2 on Windows; Microsoft.Native.Quic.MsQuic.Schannel 2.5.11-ci.156755675; Microsoft.Native.Quic.MsQuic.Schannel (NuGet) = 2.5.11-ci.156755675, ECOSYSTEM:introduced=2.5.11-ci.156755675,fixed=2.5.11-ci.159417053.
Is there a fix for CVE-2026-105016?
Yes. Microsoft.Native.Quic.MsQuic.Schannel (NuGet): upgrade to 2.5.11-ci.159417053 or later. Until then: Update to the latest servicing release of .NET 8.0, 9.0, 10.0, or 11; if your application directly references Microsoft.Native.Quic.MsQuic.Schannel, update the package to version 2.5.11-ci.159417053 or later and restart applications. Self-contained applications targeting impacted .NET versions must be recompiled and redeployed with the updated runtime.</anigation> <parameter name="timeline">[ { "kind": "disclosed", "at": "2026-10-13" } ] Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-105016 attacked?
It is attacked over the network.
Am I affected by CVE-2026-105016?
Check whether you run Microsoft .Net, Microsoft.Native.Quic.MsQuic.Schannel or Microsoft.Native.Quic.MsQuic.Schannel (NuGet) 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 2.5.11-ci.159417053 or later
    dotnet add package Microsoft.Native.Quic.MsQuic.Schannel --version 2.5.11-ci.159417053

Update to the latest servicing release of .NET 8.0, 9.0, 10.0, or 11; if your application directly references Microsoft.Native.Quic.MsQuic.Schannel, update the package to version 2.5.11-ci.159417053 or later and restart applications. Self-contained applications targeting impacted .NET versions must be recompiled and redeployed with the updated runtime.</anigation> <parameter name="timeline">[ { "kind": "disclosed", "at": "2026-10-13" } ]

Technical details

A heap-based buffer overflow (CWE-122) exists in the Microsoft QUIC HTTP/3 path handler that can be reached via crafted IPv6 QUIC packets without authentication. The vulnerability affects .NET 8.0, 9.0, 10.0, and 11 RC2 on Windows across all architectures. Successful exploitation results in remote code execution with no user interaction required.

Affected products

  • Microsoft .NET 8.0, 9.0, 10.0, 11 RC2 on Windows
  • Microsoft Microsoft.Native.Quic.MsQuic.Schannel 2.5.11-ci.156755675

Identifiers

  • CVE-2026-105016
  • GHSA-5gjq-3f94-rcf7

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