{
    "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"
                }
            }
        ]
    }
}