CVE-2026-48743
Description
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.
How to fix
- envoyproxy envoy1.35.13, 1.36.9, 1.37.5, 1.38.3 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| envoyproxy envoy | 1.35.0 ≤ v < 1.35.13, 1.36.0 ≤ v < 1.36.9, 1.37.0 ≤ v < 1.37.5, 1.38.0 ≤ v < 1.38.3 | 1.35.13, 1.36.9, 1.37.5, 1.38.3 |
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