Netty 4.2.2 through 4.2.17 HTTP/1 Host Header Authority Confusion

{
  "id": "3fd14ae8fcc5ead4742e3aac144e2d8325078990b9fdba36a64f685e9eaa3500",
  "url": "https://osv.dev/vulnerability/CVE-2026-100664",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Netty 4.2.2 through 4.2.17 HTTP/1 Host Header Authority Confusion",
    "summary": "Netty's HTTP/3 codec (io.netty:netty-codec-http3) versions 4.2.2.Final through 4.2.17.Final builds the HTTP/3 :authority pseudo-header from the HTTP/1 Host header before considering the authority of an absolute-form HTTP/1 request-target. In HttpConversionUtil.toHttp3Headers(HttpMessage, boolean) — reached via Http3FrameToHttpObjectCodec(false) — a non-empty Host header takes precedence over the request-target authority, contrary to the HTTP/1.1 rule that a server receiving an absolute-form request-target must ignore the Host header. In a Netty-based HTTP/1-to-HTTP/3 gateway, proxy, or protocol bridge, a remote client can send a request such as \"GET https://trusted.example/admin HTTP/1.1\" with \"Host: attacker.example\", causing components that validate, authorize, or route on the RFC-defined request-target authority to reach a different decision than the upstream HTTP/3 peer, which receives :authority derived from the conflicting Host header. This authority confusion can affect virtual-host routing, allow-list checks, backend selection, cache keys, and URL generation. The advisory reports integrity impact only (no code execution, memory corruption, or availability impact). Fixed in 4.2.18.Final.",
    "evidence": "osv:CVE-2026-100664",
    "products": [],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-100664",
      "aliases": [
        "CVE-2026-100664",
        "GHSA-hfr2-x62w-v49h"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/netty/netty",
              "type": "GIT",
              "events": [
                {
                  "introduced": "660edeaefad4a4cedbd61584e8f668ad2d89f0b8"
                },
                {
                  "fixed": "2521f494432e27415a567d3a81a9eb907abf20b3"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "4.2.2.Final"
                      },
                      {
                        "fixed": "4.2.18.Final"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StandardRange"
                  }
                ]
              }
            }
          ],
          "versions": [
            "netty-clang-bin",
            "netty-4.2.17.Final",
            "netty-4.2.16.Final",
            "netty-4.2.15.Final",
            "netty-4.2.14.Final",
            "netty-4.2.13.Final",
            "netty-4.2.12.Final",
            "netty-4.2.11.Final",
            "netty-4.2.10.Final",
            "netty-4.2.9.Final",
            "netty-4.2.8.Final",
            "netty-4.2.7.Final",
            "netty-4.2.6.Final",
            "netty-4.2.5.Final",
            "netty-4.2.4.Final",
            "netty-4.2.3.Final",
            "netty-4.2.2.Final"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-100664.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:51.311083530Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/100xxx/CVE-2026-100664.json",
        "https://github.com/netty/netty/security/advisories/GHSA-hfr2-x62w-v49h",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-100664",
        "https://www.vulncheck.com/advisories/netty-4.2.2-through-4.2.15-http-1-host-header-authority-confusion"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-20"
        ],
        "cna_assigner": "VulnCheck",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/100xxx/CVE-2026-100664.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-100664",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 519810,
  "published_at": "2026-09-26T13:23:30.478+00:00"
}