Netty 4.2.0 through 4.2.18 HTTP/3 Request Routing Bypass

{
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "cveMetadata": {
    "cveId": "CVE-2026-100659",
    "assignerOrgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
    "assignerShortName": "VulnCheck",
    "dateUpdated": "2026-09-26T13:23:26.859Z",
    "dateReserved": "2026-09-26T02:33:59.039Z",
    "datePublished": "2026-09-26T13:23:26.859Z",
    "state": "PUBLISHED"
  },
  "containers": {
    "cna": {
      "providerMetadata": {
        "orgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
        "shortName": "VulnCheck",
        "dateUpdated": "2026-09-26T13:23:26.859Z"
      },
      "datePublic": "2026-09-10T00:00:00.000Z",
      "title": "Netty 4.2.0 through 4.2.18 HTTP/3 Request Routing Bypass",
      "descriptions": [
        {
          "lang": "en",
          "value": "Netty's HTTP/3 codec (io.netty:netty-codec-http3) in versions 4.2.0.Final through 4.2.17.Final does not enforce the RFC 9114 requirement that the :authority pseudo-header field and a literal host header field, when both present, carry the same value. A remote unauthenticated peer can send a single HEADERS frame containing both fields with differing, attacker-controlled values; the request is accepted and delivered to the application with two conflicting authorities, allowing routing, virtual-host, and access-control decisions to be bypassed when different components in the request path consult different fields. This issue is fixed in 4.2.18.Final."
        }
      ],
      "affected": [
        {
          "vendor": "netty",
          "product": "netty",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "4.2.0.Final",
              "status": "affected",
              "versionType": "semver",
              "lessThan": "4.2.18.Final"
            },
            {
              "version": "4.2.18.Final",
              "status": "unaffected",
              "versionType": "semver"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "lang": "en",
              "description": "Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')",
              "cweId": "CWE-444",
              "type": "CWE"
            }
          ]
        }
      ],
      "references": [
        {
          "url": "https://github.com/netty/netty/security/advisories/GHSA-q9pg-8h3j-8hvm",
          "name": "GitHub Security Advisory (GHSA-q9pg-8h3j-8hvm)",
          "tags": [
            "vendor-advisory"
          ]
        },
        {
          "url": "https://www.vulncheck.com/advisories/netty-4.2.0-through-4.2.18-http-3-request-routing-bypass",
          "name": "VulnCheck Advisory: Netty 4.2.0 through 4.2.18 HTTP/3 Request Routing Bypass",
          "tags": [
            "third-party-advisory"
          ]
        }
      ],
      "metrics": [
        {
          "format": "CVSS"
        },
        {
          "format": "CVSS",
          "cvssV3_1": {
            "version": "3.1",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N",
            "attackVector": "NETWORK",
            "attackComplexity": "LOW",
            "privilegesRequired": "NONE",
            "userInteraction": "NONE",
            "scope": "UNCHANGED",
            "confidentialityImpact": "LOW",
            "integrityImpact": "LOW",
            "availabilityImpact": "NONE",
            "baseScore": 6.5,
            "baseSeverity": "MEDIUM"
          }
        }
      ],
      "credits": [
        {
          "lang": "en",
          "value": "violetagg",
          "type": "reporter"
        }
      ]
    }
  }
}