{"cve":"CVE-2026-42581","nvd":{"published":"2026-05-13T19:17:23.627","modified":"2026-09-18T13:18:20.120","status":"Modified","description":"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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","score":9.8},"cwes":["CWE-444"],"references":["https://github.com/netty/netty/security/advisories/GHSA-xxqh-mfjm-7mv9","https://access.redhat.com/errata/RHSA-2026:23808","https://access.redhat.com/errata/RHSA-2026:24502","https://access.redhat.com/errata/RHSA-2026:25123","https://access.redhat.com/errata/RHSA-2026:28010"],"products":["netty:netty"],"source":"nvd","synced_at":"2026-10-19T22:35:16.954578616+00:00"},"epss":{"cve":"CVE-2026-42581","score":0.0063,"percentile":0.50225,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-xxqh-mfjm-7mv9","url":"https://osv.dev/vulnerability/GHSA-xxqh-mfjm-7mv9","summary":"Netty HTTP/1.0 TE+CL Coexistence Bypasses Smuggling Sanitization","modified":"2026-09-10T03:51:07.381332705Z","packages":[{"ecosystem":"Maven","name":"io.netty:netty-codec-http","purl":"pkg:maven/io.netty/netty-codec-http","ranges":[">=4.2.0.Alpha1 <4.2.13.Final"],"fixed":["4.2.13.Final"]},{"ecosystem":"Maven","name":"io.netty:netty-codec-http","purl":"pkg:maven/io.netty/netty-codec-http","ranges":["<4.1.133.Final"],"fixed":["4.1.133.Final"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}