CVE-2026-32179 is a critical-severity (CVSS 9.8) vulnerability in Microsoft.Native.Quic.MsQuic.OpenSSL. A fix is available for Microsoft.Native.Quic.MsQuic.OpenSSL — see the affected versions and patch details below.
MsQuic has a Remote Elevation of Privilege Vulnerability
Real-World Exposure
Microsoft.Native.Quic.MsQuic.OpenSSL.NETMicrosoft.Native.Quic.MsQuic.Schannel.NETMicrosoft.Native.Quic.MsQuic.Schannel.NETMicrosoft.Native.Quic.MsQuic.OpenSSLReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects NuGet packages — download data is not available via public APIs for these ecosystems.
Description
Summary
Improper input validation in Microsoft QUIC allows an unauthorized attacker to elevate privileges over a network.
Details
Improper Input Validation Integer Underflow (Wrap or Wraparound) when decoding ACK frame.
Patches
- Fix underflow in ACK frame parsing - 1e6e999b
Impact
An attacker who successfully exploited this vulnerability could gain elevated privileges.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| .NETNuGet | Microsoft.Native.Quic.MsQuic.OpenSSL | ≥ 2.5.0-ci.532574&&< 2.5.7 | 2.5.7dotnet add package Microsoft.Native.Quic.MsQuic.OpenSSL --version 2.5.7 |
| .NETNuGet | Microsoft.Native.Quic.MsQuic.Schannel | ≥ 2.5.0-ci.532574&&< 2.5.7 | 2.5.7dotnet add package Microsoft.Native.Quic.MsQuic.Schannel --version 2.5.7 |
| .NETNuGet | Microsoft.Native.Quic.MsQuic.Schannel | all versions | 2.4.18dotnet add package Microsoft.Native.Quic.MsQuic.Schannel --version 2.4.18 |
| .NETNuGet | Microsoft.Native.Quic.MsQuic.OpenSSL | all versions | 2.4.18dotnet add package Microsoft.Native.Quic.MsQuic.OpenSSL --version 2.4.18 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for Microsoft.Native.Quic.MsQuic.OpenSSL, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update Microsoft.Native.Quic.MsQuic.OpenSSL to 2.5.7 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-32179 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-32179 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-32179. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-32179 in your dependencies?
O3 Security finds CVE-2026-32179 across NuGet dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.