{"id":"CVE-2026-105794","state":"PUBLISHED","title":"MsQuic: Improper Certificate Validation in Microsoft.Native.Quic.MsQuic.OpenSSL","description":"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. 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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":[{"vendor":"microsoft","product":"msquic","versions":[{"version":"< 2.4.20","status":"affected"},{"version":">= 2.5.0, < 2.5.11","status":"affected"},{"version":">= 2.6.0, < 2.6.1","status":"affected"}]}],"references":[{"url":"https://github.com/microsoft/msquic/security/advisories/GHSA-w5f4-fx9m-m4q7","name":"https://github.com/microsoft/msquic/security/advisories/GHSA-w5f4-fx9m-m4q7","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/microsoft/msquic/pull/6274","name":"https://github.com/microsoft/msquic/pull/6274","tags":["x_refsource_MISC"]},{"url":"https://github.com/microsoft/msquic/pull/6275","name":"https://github.com/microsoft/msquic/pull/6275","tags":["x_refsource_MISC"]},{"url":"https://github.com/microsoft/msquic/pull/6276","name":"https://github.com/microsoft/msquic/pull/6276","tags":["x_refsource_MISC"]},{"url":"https://github.com/microsoft/msquic/pull/6277","name":"https://github.com/microsoft/msquic/pull/6277","tags":["x_refsource_MISC"]},{"url":"https://github.com/microsoft/msquic/commit/0591586443cc73a2d2cfb679527d91a144b4a412","name":"https://github.com/microsoft/msquic/commit/0591586443cc73a2d2cfb679527d91a144b4a412","tags":["x_refsource_MISC"]},{"url":"https://github.com/microsoft/msquic/commit/508e811370df93e2ad848f5c78347d4fe4f65a91","name":"https://github.com/microsoft/msquic/commit/508e811370df93e2ad848f5c78347d4fe4f65a91","tags":["x_refsource_MISC"]},{"url":"https://github.com/microsoft/msquic/commit/90fd45498bf9b506b8556fb407088688474d6c81","name":"https://github.com/microsoft/msquic/commit/90fd45498bf9b506b8556fb407088688474d6c81","tags":["x_refsource_MISC"]},{"url":"https://github.com/microsoft/msquic/commit/a01333cf7c2659cce0ff03ef3f21e1ff15bb5b83","name":"https://github.com/microsoft/msquic/commit/a01333cf7c2659cce0ff03ef3f21e1ff15bb5b83","tags":["x_refsource_MISC"]},{"url":"https://github.com/microsoft/msquic/releases/tag/v2.4.20","name":"https://github.com/microsoft/msquic/releases/tag/v2.4.20","tags":["x_refsource_MISC"]},{"url":"https://github.com/microsoft/msquic/releases/tag/v2.5.11","name":"https://github.com/microsoft/msquic/releases/tag/v2.5.11","tags":["x_refsource_MISC"]},{"url":"https://github.com/microsoft/msquic/releases/tag/v2.6.1","name":"https://github.com/microsoft/msquic/releases/tag/v2.6.1","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV4_0":{"attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"PRESENT","privilegesRequired":"NONE","userInteraction":"NONE","vulnConfidentialityImpact":"HIGH","vulnIntegrityImpact":"HIGH","vulnAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","subAvailabilityImpact":"NONE","baseScore":9.1,"baseSeverity":"CRITICAL","vectorString":"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","version":"4.0"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-295","lang":"en","description":"CWE-295: Improper Certificate Validation","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-10-06T14:14:54.483Z"},"source":{"advisory":"GHSA-w5f4-fx9m-m4q7","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-10-06T17:34:05.356189Z","id":"CVE-2026-105794","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-06T17:40:05.706Z"}}]}}}