MsQuic: Improper Certificate Validation in Microsoft.Native.Quic.MsQuic.OpenSSL
Summary
Improper TLS hostname verification allows a man-in-the-middle (MITM) attack on MsQuic.
Details
Only MsQuic with the OpenSSL and QuicTLS TLS backends is affected (the Schannel backend is not affected).
Patches
2.6.1, 2.5.11, and 2.4.20
Impact
An on-path attacker could spoof a server identity by using a certificate that doesn't match the intended target server hostname.
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| .NET (NuGet) | Microsoft.Native.Quic.MsQuic.OpenSSL | < 2.4.20, >= 2.5.0, < 2.5.11, >= 2.6.0, < 2.6.1 | 2.4.20, 2.5.11, 2.6.1 |
References
- https://github.com/microsoft/msquic/security/advisories/GHSA-w5f4-fx9m-m4q7
- https://nvd.nist.gov/vuln/detail/CVE-2026-105794
- https://github.com/microsoft/msquic/pull/6274
- https://github.com/microsoft/msquic/pull/6275
- https://github.com/microsoft/msquic/pull/6276
- https://github.com/microsoft/msquic/pull/6277
- https://github.com/microsoft/msquic/commit/0591586443cc73a2d2cfb679527d91a144b4a412
- https://github.com/microsoft/msquic/commit/508e811370df93e2ad848f5c78347d4fe4f65a91
- https://github.com/microsoft/msquic/commit/90fd45498bf9b506b8556fb407088688474d6c81
- https://github.com/microsoft/msquic/commit/a01333cf7c2659cce0ff03ef3f21e1ff15bb5b83
- https://github.com/microsoft/msquic
- https://github.com/microsoft/msquic/releases/tag/v2.4.20
- https://github.com/microsoft/msquic/releases/tag/v2.5.11
- https://github.com/microsoft/msquic/releases/tag/v2.6.1
- CVSS vector
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N- Weakness (CWE)
CWE-295- Platform
- .NET (NuGet)
- Package
Microsoft.Native.Quic.MsQuic.OpenSSL- Disclosed
- 06.10.2026
- Updated
- 11.10.2026 11:23
Sources and licenses
OSV / GitHub Advisory Database - GHSA-w5f4-fx9m-m4q7 - CC BY 4.0
Vulnerability history: Microsoft.Native.Quic.MsQuic.OpenSSL
All published vulnerabilities of this package (.NET (NuGet)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 6
- First → latest
- 10.2023 10.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- Critical 3
- High 3
Disclosures per year
- 2023: 2
- 2024: 1
- 2025: 0
- 2026: 3
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MsQuic: Improper Certificate Validation in Microsoft.Native.Quic.MsQuic.OpenSSL this entry
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