{"id":"CVE-2026-50020","aliases":["GHSA-hvcg-qmg6-jm4c"],"url":"https://o3.security/vulnerability/CVE-2026-50020","summary":"Netty's HttpObjectDecoder skips arbitrary initial control characters when only initial CRLF characters are permitted","details":"Netty is a network application framework for development of protocol servers and clients. Prior to versions 4.1.135.Final and 4.2.15.Final, before reading the first request-line, `HttpObjectDecoder` skips every byte for which `Character.isISOControl(b)` is `true` (0x00–0x1F and 0x7F) as well as all whitespace. RFC 9112 §2.2 only asks servers to ignore empty CRLF lines preceding the request-line — a carefully scoped robustness allowance intended to handle HTTP/1.0 POST workarounds. Silently absorbing NUL bytes, SOH, STX, and other non-CRLF control characters goes significantly beyond this, and can be exploited for request-boundary confusion in pipelined or multiplexed transports where a front-end component treats those bytes differently. Versions 4.1.135.Final and 4.2.15.Final patch the issue.","published":"2026-06-12T14:55:32.165Z","modified":"2026-08-12T03:51:24.374464544Z","cvss":{"score":5.3,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N"},"epss":{"score":0.00232,"percentile":0.13968,"asOf":"2026-09-02"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"Maven","name":"io.netty:netty-codec-http","fixedVersion":"4.2.15.Final"},{"ecosystem":"Maven","name":"io.netty:netty-codec-http","fixedVersion":"4.1.135.Final"}],"fix":null,"references":[{"type":"WEB","url":"https://github.com/netty/netty/releases/tag/netty-4.1.135.Final"},{"type":"WEB","url":"https://github.com/netty/netty/releases/tag/netty-4.2.15.Final"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/50xxx/CVE-2026-50020.json"},{"type":"ADVISORY","url":"https://github.com/netty/netty/security/advisories/GHSA-hvcg-qmg6-jm4c"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-50020"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:24.374464544Z"}}