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High

Netty 4.2.0 through 4.2.16 TLS Hostname Verification Bypass

Type: advisorySources: OSV

Netty (io.netty:netty-handler) versions from 4.2.0.Final through 4.2.16.Final and versions through 4.1.136.Final disable TLS hostname verification on the SslProvider.OPENSSL client path when a plain (non-extended) X509TrustManager is used and Unsafe-based trust-manager wrapping is unavailable (Java 25+). In this configuration the OpenSSL client does not perform hostname verification, allowing a man-in-the-middle attacker to present a certificate issued for a different hostname that is accepted without validation. Fixed in 4.2.17.Final and 4.1.137.Final.

Products
Not specified
Affected versions
Not specified
Fixed versions
Not specified
CVEs
CVE-2026-62243
Confirmed fixed CVEs
Not specified
Updated in this feed
5 Nov 2026, 01:23 UTC · Revision 1

Source evidence

Netty 4.2.0 through 4.2.16 TLS Hostname Verification Bypass

core-osv · Original source

Published 22 Aug 2026, 12:26 UTC

Netty (io.netty:netty-handler) versions from 4.2.0.Final through 4.2.16.Final and versions through 4.1.136.Final disable TLS hostname verification on the SslProvider.OPENSSL client path when a plain (non-extended) X509TrustManager is used and Unsafe-based trust-manager wrapping is unavailable (Java 25+). In this configuration the OpenSSL client does not perform hostname verification, allowing a man-in-the-middle attacker to present a certificate issued for a different hostname that is accepted without validation. Fixed in 4.2.17.Final and 4.1.137.Final.

osv:CVE-2026-62243
Complete source record
{
  "id": "b93ba1d3a401f3179a01cd0037e8b85e148cbe82a1f14aab6c3c4a5b9fa599cc",
  "url": "https://osv.dev/vulnerability/CVE-2026-62243",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Netty 4.2.0 through 4.2.16 TLS Hostname Verification Bypass",
    "summary": "Netty (io.netty:netty-handler) versions from 4.2.0.Final through 4.2.16.Final and versions through 4.1.136.Final disable TLS hostname verification on the SslProvider.OPENSSL client path when a plain (non-extended) X509TrustManager is used and Unsafe-based trust-manager wrapping is unavailable (Java 25+). In this configuration the OpenSSL client does not perform hostname verification, allowing a man-in-the-middle attacker to present a certificate issued for a different hostname that is accepted without validation. Fixed in 4.2.17.Final and 4.1.137.Final.",
    "evidence": "osv:CVE-2026-62243",
    "products": [],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-62243",
      "aliases": [
        "CVE-2026-62243",
        "GHSA-p85m-gvr3-788c"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/netty/netty",
              "type": "GIT",
              "events": [
                {
                  "introduced": "09e64d259c99be8b5b2a471a78f11e65eb82598a"
                },
                {
                  "fixed": "3703d79669ee024f6483c9d8697ac58ba546df33"
                },
                {
                  "introduced": "0"
                },
                {
                  "fixed": "5471f0a6ffa4ab39db22c468c6c851af4ecae709"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "4.2.0.Final"
                      },
                      {
                        "fixed": "4.2.16.Final"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StandardRange"
                  },
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "4.1.137.Final"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StandardRange"
                  }
                ]
              }
            }
          ],
          "versions": [
            "netty-4.1.136.Final",
            "netty-4.1.135.Final",
            "netty-4.2.15.Final",
            "netty-4.1.134.Final",
            "netty-4.2.14.Final",
            "netty-4.1.133.Final",
            "netty-4.2.13.Final",
            "netty-4.2.12.Final",
            "netty-4.1.132.Final",
            "netty-4.2.11.Final",
            "netty-4.1.131.Final",
            "netty-4.2.10.Final",
            "netty-4.2.9.Final",
            "netty-4.1.130.Final",
            "netty-4.2.8.Final",
            "netty-4.1.129.Final",
            "netty-4.1.128.Final",
            "netty-4.2.7.Final",
            "netty-4.2.6.Final",
            "netty-4.1.127.Final",
            "netty-4.2.5.Final",
            "netty-4.1.126.Final",
            "netty-4.1.125.Final",
            "netty-4.2.4.Final",
            "netty-4.1.124.Final",
            "netty-4.1.123.Final",
            "netty-4.2.3.Final",
            "netty-4.2.2.Final",
            "netty-4.1.122.Final",
            "netty-4.2.1.Final",
            "netty-4.1.121.Final",
            "netty-4.1.120.Final",
            "netty-4.2.0.Final",
            "netty-4.1.119.Final",
            "netty-4.1.118.Final",
            "netty-4.1.117.Final",
            "netty-4.1.116.Final",
            "netty-4.1.115.Final",
            "netty-4.1.114.Final",
            "netty-4.1.113.Final",
            "netty-4.1.112.Final",
            "netty-4.1.111.Final",
            "netty-4.1.110.Final",
            "netty-4.1.109.Final",
            "netty-4.1.108.Final",
            "netty-4.1.107.Final",
            "netty-4.1.106.Final",
            "netty-4.1.105.Final",
            "netty-4.1.104.Final",
            "netty-4.1.103.Final",
            "netty-4.1.102.Final",
            "netty-4.1.101.Final",
            "netty-4.1.100.Final",
            "netty-4.1.99.Final",
            "netty-4.1.98.Final",
            "netty-4.1.97.Final",
            "netty-4.1.96.Final",
            "netty-4.1.95.Final",
            "netty-4.1.94.Final",
            "netty-4.1.93.Final",
            "netty-4.1.92.Final",
            "netty-4.1.91.Final",
            "netty-4.1.90.Final",
            "netty-4.1.89.Final",
            "netty-4.1.88.Final",
            "netty-4.1.87.Final",
            "netty-4.1.86.Final",
            "netty-4.1.85.Final",
            "netty-4.1.84.Final",
            "netty-4.1.83.Final",
            "netty-4.1.82.Final",
            "netty-4.1.81.Final",
            "netty-4.1.80.Final",
            "netty-4.1.79.Final",
            "netty-4.1.78.Final",
            "netty-4.1.77.Final",
            "netty-4.1.76.Final",
            "netty-4.1.75.Final",
            "netty-4.1.74.Final",
            "netty-4.1.73.Final",
            "netty-4.1.72.Final",
            "netty-4.1.71.Final",
            "netty-4.1.70.Final",
            "netty-4.1.69.Final",
            "netty-4.1.68.Final",
            "netty-4.1.67.Final",
            "netty-4.1.66.Final",
            "netty-4.1.65.Final",
            "netty-4.1.64.Final",
            "netty-4.1.63.Final",
            "netty-4.1.62.Final",
            "netty-4.1.61.Final",
            "netty-4.1.60.Final",
            "netty-4.1.59.Final",
            "netty-4.1.58.Final",
            "netty-4.1.57.Final",
            "netty-4.1.56.Final",
            "netty-4.1.55.Final",
            "netty-4.1.54.Final",
            "netty-4.1.53.Final",
            "netty-4.1.52.Final",
            "netty-4.1.51.Final",
            "netty-4.1.50.Final",
            "netty-4.1.49.Final",
            "netty-4.1.48.Final",
            "netty-4.1.47.Final",
            "netty-4.1.46.Final",
            "netty-4.1.45.Final",
            "netty-4.1.44.Final",
            "netty-4.1.43.Final",
            "netty-4.1.42.Final",
            "netty-4.1.41.Final",
            "netty-4.1.40.Final",
            "netty-4.1.39.Final",
            "netty-4.1.38.Final",
            "netty-4.1.37.Final",
            "netty-4.1.36.Final",
            "netty-4.1.35.Final",
            "netty-4.1.34.Final",
            "netty-4.1.33.Final",
            "netty-4.1.32.Final",
            "netty-4.1.31.Final",
            "netty-4.1.30.Final",
            "netty-4.1.29.Final",
            "netty-4.1.28.Final",
            "netty-4.1.27.Final",
            "netty-4.1.26.Final",
            "netty-4.1.25.Final",
            "netty-4.1.24.Final",
            "netty-4.1.23.Final",
            "netty-4.1.22.Final",
            "netty-4.1.21.Final",
            "netty-4.1.20.Final",
            "netty-4.1.19.Final",
            "netty-4.1.18.Final",
            "netty-4.1.17.Final",
            "netty-4.1.16.Final",
            "netty-4.1.15.Final",
            "netty-4.1.14.Final",
            "netty-4.1.13.Final",
            "netty-4.1.12.Final",
            "netty-4.1.11.Final",
            "netty-4.1.10.Final",
            "netty-4.1.9.Final",
            "netty-4.1.8.Final",
            "netty-4.1.7.Final",
            "netty-4.1.6.Final",
            "netty-4.1.5.Final",
            "netty-4.1.4.Final",
            "netty-4.1.3.Final",
            "netty-4.1.2.Final",
            "netty-4.1.1.Final",
            "netty-4.1.0.Final",
            "netty-4.1.0.CR7",
            "netty-4.1.0.CR6",
            "netty-4.1.0.CR5",
            "netty-4.1.0.CR4",
            "netty-4.1.0.CR3",
            "netty-4.1.0.CR2",
            "netty-4.1.0.CR1",
            "netty-4.1.0.Beta8",
            "netty-4.1.0.Beta7",
            "netty-4.1.0.Beta6",
            "netty-4.1.0.Beta5",
            "netty-4.1.0.Beta4",
            "netty-4.1.0.Beta3",
            "netty-4.1.0.Beta2",
            "netty-4.1.0.Beta1",
            "netty-4.0.15.Final",
            "netty-4.0.14.Final",
            "netty-4.0.14.Beta1",
            "netty-4.0.13.Final",
            "netty-4.0.12.Final",
            "netty-4.0.11.Final",
            "netty-4.0.10.Final",
            "netty-4.0.8.Final",
            "netty-4.0.7.Final",
            "netty-4.0.6.Final",
            "netty-4.0.5.Final",
            "netty-4.0.4.Final",
            "netty-4.0.3.Final",
            "netty-4.0.2.Final",
            "netty-4.0.1.Final",
            "netty-4.0.0.Final",
            "netty-4.0.0.CR9",
            "netty-4.0.0.CR8",
            "netty-4.0.0.CR7",
            "netty-4.0.0.CR5",
            "netty-4.0.0.CR4",
            "netty-4.0.0.CR3",
            "netty-4.0.0.CR2",
            "netty-4.0.0.CR1",
            "netty-4.0.0.Beta3",
            "netty-4.0.0.Beta2",
            "netty-4.0.0.Beta1",
            "netty-4.0.0.Alpha8",
            "netty-4.0.0.Alpha7",
            "netty-4.0.0.Alpha6",
            "netty-4.0.0.Alpha5",
            "netty-4.0.0.Alpha4",
            "netty-4.0.0.Alpha3",
            "netty-4.0.0.Alpha2",
            "netty-4.0.0.Alpha1"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-62243.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:41.491743461Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/62xxx/CVE-2026-62243.json",
        "https://github.com/netty/netty/security/advisories/GHSA-p85m-gvr3-788c",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-62243",
        "https://www.vulncheck.com/advisories/netty-through-tls-hostname-verification-bypass"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-297"
        ],
        "cna_assigner": "VulnCheck",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/62xxx/CVE-2026-62243.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-62243",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 509045,
  "published_at": "2026-08-22T12:26:43.072+00:00"
}