{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "0"
              },
              {
                "fixed": "4.1.137.Final"
              },
              {
                "introduced": "4.2.0.Final"
              },
              {
                "fixed": "4.2.17.Final"
              }
            ],
            "source": [
              "AFFECTED_FIELD",
              "REFERENCES"
            ]
          },
          "events": [
            {
              "introduced": "0"
            },
            {
              "introduced": "09e64d259c99be8b5b2a471a78f11e65eb82598a"
            },
            {
              "fixed": "5471f0a6ffa4ab39db22c468c6c851af4ecae709"
            },
            {
              "fixed": "e0789d32c72f46fd2e7c99b6fdbbf7e2f4409e44"
            },
            {
              "fixed": "1b5abc6443b63726c72cdd285af2feb7ddbb8ff7"
            },
            {
              "fixed": "9e0519239108a69b7e9bbc5e9182ee139a0d7961"
            }
          ],
          "repo": "https://github.com/netty/netty",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-c4c3-7fpv-j4q5"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-754"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/75xxx/CVE-2026-75595.json"
  },
  "details": "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.",
  "id": "CVE-2026-75595",
  "modified": "2026-08-22T03:31:14.153766259Z",
  "published": "2026-08-19T21:00:27.627Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/netty/netty/releases/tag/netty-4.1.137.Final"
    },
    {
      "type": "WEB",
      "url": "https://github.com/netty/netty/releases/tag/netty-4.2.17.Final"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/75xxx/CVE-2026-75595.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/netty/netty/security/advisories/GHSA-c4c3-7fpv-j4q5"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-75595"
    },
    {
      "type": "FIX",
      "url": "https://github.com/netty/netty/commit/1b5abc6443b63726c72cdd285af2feb7ddbb8ff7"
    },
    {
      "type": "FIX",
      "url": "https://github.com/netty/netty/commit/9e0519239108a69b7e9bbc5e9182ee139a0d7961"
    },
    {
      "type": "FIX",
      "url": "https://github.com/netty/netty/pull/17213"
    },
    {
      "type": "FIX",
      "url": "https://github.com/netty/netty/pull/17217"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Netty: SNI Routing Bypass via Fragmented TLS ClientHello Causing Fallback to Default SslContext"
}