Answer in brief
CVE-2026-105794 records a Critical severity (CVSS 9.1) vulnerability in MsQuic: Improper Certificate Validation in Microsoft.Native.Quic.MsQuic.OpenSSL. The current sources do not mark it as known exploited. The current feed maps microsoft/msquic (generic), Microsoft.Native.Quic.MsQuic.OpenSSL (nuget), Microsoft.Native.Quic.MsQuic.OpenSSL (nuget), Microsoft.Native.Quic.MsQuic.OpenSSL (nuget). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 9.1. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps microsoft/msquic (generic), Microsoft.Native.Quic.MsQuic.OpenSSL (nuget), Microsoft.Native.Quic.MsQuic.OpenSSL (nuget), Microsoft.Native.Quic.MsQuic.OpenSSL (nuget). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| microsoft/msquicgeneric | <2.4.20 || >=2.5.0 <2.5.11 || >=2.6.0 <2.6.1 | 2.4.20, 2.5.11, 2.6.1 |
| Microsoft.Native.Quic.MsQuic.OpenSSLnuget | <2.4.20 | 2.4.20 |
| Microsoft.Native.Quic.MsQuic.OpenSSLnuget | >=2.5.0,<2.5.11 | 2.5.11 |
| Microsoft.Native.Quic.MsQuic.OpenSSLnuget | >=2.6.0,<2.6.1 | 2.6.1 |
Published upstream
Oct 6, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Oct 6, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Oct 6, 2026
MsQuic is a cross-platform C implementation of the IETF QUIC protocol exposed to C, C++, C#, and Rust. Prior to 2.4.20, 2.5.11, and 2.6.1, MsQuic clients using the OpenSSL or QuicTLS TLS backend do not properly verify that a server certificate matches the intended target server hostname. An on-path attacker can therefore present a certificate that does not match the intended target hostname and spoof the server in a man-in-the-middle attack. The Schannel backend is not affected. This issue is fixed in versions 2.4.20, 2.5.11, and 2.6.1.
Quoted source text, attributed separately from HOL analysis.