{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-75595","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","state":"PUBLISHED","assignerShortName":"GitHub_M","dateReserved":"2026-08-17T23:49:03.449Z","datePublished":"2026-08-19T21:00:27.627Z","dateUpdated":"2026-08-20T14:06:16.963Z"},"containers":{"cna":{"title":"Netty: SNI Routing Bypass via Fragmented TLS ClientHello Causing Fallback to Default SslContext","problemTypes":[{"descriptions":[{"cweId":"CWE-754","lang":"en","description":"CWE-754: Improper Check for Unusual or Exceptional Conditions","type":"CWE"}]}],"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"}}],"references":[{"name":"https://github.com/netty/netty/security/advisories/GHSA-c4c3-7fpv-j4q5","tags":["x_refsource_CONFIRM"],"url":"https://github.com/netty/netty/security/advisories/GHSA-c4c3-7fpv-j4q5"},{"name":"https://github.com/netty/netty/pull/17213","tags":["x_refsource_MISC"],"url":"https://github.com/netty/netty/pull/17213"},{"name":"https://github.com/netty/netty/pull/17217","tags":["x_refsource_MISC"],"url":"https://github.com/netty/netty/pull/17217"},{"name":"https://github.com/netty/netty/commit/1b5abc6443b63726c72cdd285af2feb7ddbb8ff7","tags":["x_refsource_MISC"],"url":"https://github.com/netty/netty/commit/1b5abc6443b63726c72cdd285af2feb7ddbb8ff7"},{"name":"https://github.com/netty/netty/commit/9e0519239108a69b7e9bbc5e9182ee139a0d7961","tags":["x_refsource_MISC"],"url":"https://github.com/netty/netty/commit/9e0519239108a69b7e9bbc5e9182ee139a0d7961"},{"name":"https://github.com/netty/netty/releases/tag/netty-4.1.137.Final","tags":["x_refsource_MISC"],"url":"https://github.com/netty/netty/releases/tag/netty-4.1.137.Final"},{"name":"https://github.com/netty/netty/releases/tag/netty-4.2.17.Final","tags":["x_refsource_MISC"],"url":"https://github.com/netty/netty/releases/tag/netty-4.2.17.Final"}],"affected":[{"vendor":"netty","product":"netty","versions":[{"version":"< 4.1.137.Final","status":"affected"},{"version":">= 4.2.0.Final, < 4.2.17.Final","status":"affected"}]}],"providerMetadata":{"orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","shortName":"GitHub_M","dateUpdated":"2026-08-19T21:00:27.627Z"},"descriptions":[{"lang":"en","value":"Netty is an asynchronous, event-driven network application framework. Prior to 4.1.137.Fina and 4.2.17.Final, io.netty.handler.ssl.SslClientHelloHandler#decode checks the wrong offset before reading the four-byte TLS handshake header, so a ClientHello whose handshake header spans records can cause an IndexOutOfBoundsException and invoke select(ctx, null). This selects the default SslContext instead of the SNI-specific context. In deployments where per-SNI clientAuth=REQUIRE is the sole mutual TLS gate, the default SslContext uses clientAuth=NONE or clientAuth=OPTIONAL, and no application-layer certificate verification exists, an unauthenticated remote attacker can bypass the protected route's mutual TLS requirement. This issue is fixed in versions 4.1.137.Final and 4.2.17.Final."}],"source":{"advisory":"GHSA-c4c3-7fpv-j4q5","discovery":"UNKNOWN"}},"adp":[{"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-08-20T14:05:51.091097Z","id":"CVE-2026-75595","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"title":"CISA ADP Vulnrichment","providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2026-08-20T14:06:16.963Z"}}]}}