Netty is an asynchronous, event-driven network application framework. Prior to 4.2.13.Final and 4.1.133.Final, HttpObjectDecoder strips a conflicting Content-Length header when a request carries both Transfer-Encoding: chunked and Content-Length, but only for HTTP/1.1 messages. The guard is absent for HTTP/1.0. An attacker that sends an HTTP/1.0 request with both headers causes Netty to decode the body as chunked while leaving Content-Length intact in the forwarded HttpMessage. Any downstream proxy or handler that trusts Content-Length over Transfer-Encoding will disagree on message boundaries, enabling request smuggling. This vulnerability is fixed in 4.2.13.Final and 4.1.133.Final.
{
"cna_assigner": "GitHub_M",
"cwe_ids": [
"CWE-444"
],
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/42xxx/CVE-2026-42581.json"
}{
"source": "CPE_RANGE",
"extracted_events": [
{
"introduced": "0"
},
{
"fixed": "4.1.133"
},
{
"introduced": "4.2.0"
},
{
"fixed": "4.2.13"
}
],
"cpe": "cpe:2.3:a:netty:netty:*:*:*:*:*:*:*:*"
}