{"id":"CVE-2026-50020","state":"PUBLISHED","title":"Netty's HttpObjectDecoder skips arbitrary initial control characters when only initial CRLF characters are permitted","description":"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.","publishedAt":"2026-06-12T14:55:32.165Z","updatedAt":"2026-06-12T15:56:43.051Z","severity":{"score":5.3,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["netty netty"],"affected":[{"vendor":"netty","product":"netty","versions":[{"version":">= 4.2.0.Final, < 4.2.15.Final","status":"affected"},{"version":"< 4.1.135.Final","status":"affected"}]}],"references":["https://github.com/netty/netty/security/advisories/GHSA-hvcg-qmg6-jm4c","https://github.com/netty/netty/releases/tag/netty-4.1.135.Final","https://github.com/netty/netty/releases/tag/netty-4.2.15.Final"],"weaknesses":["CWE-444"],"ingestedAt":"2026-10-29T20:12:16.098Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/50xxx/CVE-2026-50020.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-50020","state":"PUBLISHED","datePublished":"2026-06-12T14:55:32.165Z","dateUpdated":"2026-06-12T15:56:43.051Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-06-02T22:46:02.579Z"},"containers":{"cna":{"title":"Netty's HttpObjectDecoder skips arbitrary initial control characters when only initial CRLF characters are permitted","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"netty","product":"netty","versions":[{"version":">= 4.2.0.Final, < 4.2.15.Final","status":"affected"},{"version":"< 4.1.135.Final","status":"affected"}]}],"references":[{"url":"https://github.com/netty/netty/security/advisories/GHSA-hvcg-qmg6-jm4c","name":"https://github.com/netty/netty/security/advisories/GHSA-hvcg-qmg6-jm4c","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/netty/netty/releases/tag/netty-4.1.135.Final","name":"https://github.com/netty/netty/releases/tag/netty-4.1.135.Final","tags":["x_refsource_MISC"]},{"url":"https://github.com/netty/netty/releases/tag/netty-4.2.15.Final","name":"https://github.com/netty/netty/releases/tag/netty-4.2.15.Final","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":5.3,"baseSeverity":"MEDIUM","confidentialityImpact":"NONE","integrityImpact":"LOW","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-444","lang":"en","description":"CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-06-12T14:55:32.165Z"},"source":{"advisory":"GHSA-hvcg-qmg6-jm4c","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","references":[{"url":"https://github.com/netty/netty/security/advisories/GHSA-hvcg-qmg6-jm4c","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-06-12T15:56:10.783796Z","id":"CVE-2026-50020","options":[{"Exploitation":"poc"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-06-12T15:56:43.051Z"}}]}}}