CVE-2026-105794 json
MsQuic: Improper Certificate Validation in Microsoft.Native.Quic.MsQuic.OpenSSL
published last mo. modified last mo. also GHSA-w5f4-fx9m-m4q7 , EUVD-2026-93422
- cvss
- 9.1
- version 4.0, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 1.0%
- EPSS 1.0% chance of exploitation in 30 days, percentile 63%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
- nuget Microsoft.Native.Quic.MsQuic.OpenSSL 2.4.20, 2.5.11, 2.6.1
- github.com/microsoft/msquic@0591586 commit
- github.com/microsoft/msquic@508e811 commit
- github.com/microsoft/msquic@90fd454 commit
- github.com/microsoft/msquic@a01333c commit
- github.com/microsoft/msquic#6274 pull request
- github.com/microsoft/msquic#6275 pull request
- github.com/microsoft/msquic#6276 pull request
- github.com/microsoft/msquic#6277 pull request
- github.com/microsoft/msquic/releases/tag/v2.4.20 release
- github.com/microsoft/msquic/releases/tag/v2.5.11 release
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Check with FencerCISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
- Assessed
- last mo.
Exploit prediction
1.00% chance of exploitation in the next 30 days, higher than 63% of all scored CVEs (FIRST EPSS, 2026-11-09).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 4.0 | 9.1 | 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 |
| CNA | 4.0 | 9.1 | 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| 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 |
Affected products
- microsoft msquic
Classification
- Weakness
-
- CWE-295 Improper Certificate Validation
References
-
github.com
/microsoft/msquic/pull/6274
web
-
github.com
/microsoft/msquic/pull/6275
web
-
github.com
/microsoft/msquic/pull/6276
web
-
github.com
/microsoft/msquic/pull/6277
web
-
github.com
/microsoft/msquic/commit/0591586443cc73a2d2cfb679527d91a144b4a412
web
-
github.com
/microsoft/msquic/commit/508e811370df93e2ad848f5c78347d4fe4f65a91
web
-
github.com
/microsoft/msquic/commit/90fd45498bf9b506b8556fb407088688474d6c81
web
-
github.com
/microsoft/msquic/commit/a01333cf7c2659cce0ff03ef3f21e1ff15bb5b83
web
-
github.com
/microsoft/msquic/security/advisories/GHSA-w5f4-fx9m-m4q7
web
-
github.com
/microsoft/msquic/releases/tag/v2.4.20
web
-
github.com
/microsoft/msquic/releases/tag/v2.5.11
web
-
github.com
/microsoft/msquic/releases/tag/v2.6.1
web
-
nvd.nist.gov
/vuln/detail/CVE-2026-105794
advisory
-
github.com
/microsoft/msquic
package
Sources
- CVE List CVE-2026-105794
- GitHub Advisory GHSA-w5f4-fx9m-m4q7
- NVD CVE-2026-105794
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