CVE-2026-105794
Published:October 06, 2026
Updated:October 09, 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.
Affected Packages
https://github.com/microsoft/msquic.git (GITHUB):
Affected version(s) >=v2.5.0 <v2.5.11Fix Suggestion:
Update to version v2.5.11https://github.com/microsoft/msquic.git (GITHUB):
Affected version(s) >=v2.6.0-rc <v2.6.1Fix Suggestion:
Update to version v2.6.1https://github.com/microsoft/msquic.git (GITHUB):
Affected version(s) >=v2.0.0 <v2.4.20Fix Suggestion:
Update to version v2.4.20microsoft.native.quic.msquic.openssl (NUGET):
Affected version(s) >=2.6.0-rc <2.6.1Fix Suggestion:
Update to version 2.6.1microsoft.native.quic.msquic.openssl (NUGET):
Affected version(s) >=2.5.0-arm64-ci.126754598 <2.5.11Fix Suggestion:
Update to version 2.5.11microsoft.native.quic.msquic.openssl (NUGET):
Affected version(s) >=2.0.0-ci.243644 <2.4.20Fix Suggestion:
Update to version 2.4.20Related Resources (15)
Do you need more information?
Contact UsCVSS v4
Base Score:
9.1
Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
PRESENT
Privileges Required
NONE
User Interaction
NONE
Vulnerable System Confidentiality
HIGH
Vulnerable System Integrity
HIGH
Vulnerable System Availability
NONE
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
9.1
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
NONE
Weakness Type (CWE)
Improper Certificate Validation
EPSS
Base Score:
1.00