{"id":"BIT-envoy-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":["CVE-2026-48743","GHSA-8phg-2h2q-jgxf"],"modified":"2026-09-08T08:47:28.694153390Z","published":"2026-06-30T23:39:39.412Z","database_specific":{"severity":"High","cpes":["cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:*"]},"references":[{"type":"ADVISORY","url":"https://github.com/envoyproxy/envoy/security/advisories/GHSA-8phg-2h2q-jgxf"},{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-48743"}],"affected":[{"package":{"name":"envoy","ecosystem":"Bitnami","purl":"pkg:bitnami/envoy"},"ranges":[{"type":"SEMVER","events":[{"introduced":"1.35.0"},{"fixed":"1.35.11"},{"introduced":"1.36.0"},{"fixed":"1.36.7"},{"introduced":"1.37.0"},{"fixed":"1.37.3"},{"introduced":"1.38.0"},{"fixed":"1.38.1"}]}],"database_specific":{"source":"https://github.com/bitnami/vulndb/tree/main/data/envoy/BIT-envoy-2026-48743.json"},"severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:H/A:N"}]}],"schema_version":"1.9.0"}