{"id":"CVE-2026-48743","summary":"Envoy: HTTP/3 to HTTP/1 request smuggling via headers-only request with nonzero Content-Length","details":"Envoy is an open source edge and service proxy designed for cloud-native applications. Prior to 1.35.11, 1.36.7, 1.37.3, and 1.38.1, Envoy can translate a downstream HTTP/3 request that is complete at the transport layer (HEADERS with FIN / headers-only close) but still carries a nonzero Content-Length into a complete upstream HTTP/1 request with unresolved body debt. In an HTTP/1 upstream deployment where the origin replies before reading the declared body and keeps the connection reusable, the beginning of the next Envoy-generated upstream request can be consumed as the first request's body. The remaining bytes are then parsed by the origin as a new HTTP/1 request. This was reproduced as a route-bypass/desync: direct /pwn was denied by Envoy, but the second downstream H3 stream received the response for backend-parsed GET /pwn HTTP/1.1. This vulnerability is fixed in 1.35.11, 1.36.7, 1.37.3, and 1.38.1.","aliases":["BIT-envoy-2026-48743","GHSA-8phg-2h2q-jgxf"],"modified":"2026-07-08T08:26:26.159863705Z","published":"2026-06-26T17:34:22.470Z","related":["openSUSE-SU-2026:11141-1"],"database_specific":{"cna_assigner":"GitHub_M","cwe_ids":["CWE-444"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/48xxx/CVE-2026-48743.json"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/48xxx/CVE-2026-48743.json"},{"type":"ADVISORY","url":"https://github.com/envoyproxy/envoy/security/advisories/GHSA-8phg-2h2q-jgxf"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-48743"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/envoyproxy/envoy","events":[{"introduced":"84305a6cb64bd55aaf606bdd53de7cd6080427a1"},{"fixed":"adb998f2875986005be294d10231a9c9a497e30d"},{"introduced":"63ee0dc79dce88117c6bd2df5a742f8eb67ea980"},{"fixed":"57198c441a298a75097c690726d90974549a9778"},{"introduced":"6d9bb7d9a85d616b220d1f8fe67b61f82bbdb8d3"},{"fixed":"f97695a50e11f5ff6719e129a466bf9204b64a7f"},{"introduced":"f1dd21b16c244bda00edfb5ffce577e12d0d2ec2"},{"fixed":"0ebfcfe5b0484b89ca85b761da9e05ce75dbda8d"}],"database_specific":{"source":"CPE_RANGE","extracted_events":[{"introduced":"1.35.0"},{"fixed":"1.35.13"},{"introduced":"1.36.0"},{"fixed":"1.36.9"},{"introduced":"1.37.0"},{"fixed":"1.37.5"},{"introduced":"1.38.0"},{"fixed":"1.38.3"}],"cpe":"cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:*"}}],"versions":["v1.38.2","v1.37.4","v1.36.8","v1.35.12","v1.38.1","v1.37.3","v1.36.7","v1.35.11","v1.38.0","v1.37.2","v1.36.6","v1.35.10","v1.37.1","v1.36.5","v1.35.9","v1.37.0","v1.36.4","v1.35.8","v1.36.3","v1.35.7","v1.35.6","v1.36.2","v1.36.1","v1.35.5","v1.36.0","v1.35.4","v1.35.3","v1.35.2","v1.35.1","v1.35.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-48743.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:H/A:N"}]}