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CVE-2026-48743

HIGH
7.5
CVSS 3.1
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.

Metadata

CVE ID
CVE-2026-48743
State
PUBLISHED
Assigner
GitHub_M
Reserved
2026-05-22 19:10 UTC
Published
2026-06-26 17:34 UTC
Last updated
2026-06-26 17:34 UTC
Primary CWE
CWE-444
CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP…
Vendor / Product
envoyproxy / envoy
Sources
cve.org  ·  NVD

Severity & Metrics

7.5 HIGH CVSS 3.1
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:H/A:N
Affected products (1)
VendorProductPlatformVersions
envoyproxy envoy — >= 1.38.0, < 1.38.1, >= 1.37.0, < 1.37.3, >= 1.36.0, < 1.36.7, >= 1.35.0, < 1.35.11
Weakness (CWE)
CWESourceDescription
CWE-444 cna CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
CVSS scores (1)
ScoreSeverityVersionSourceVector
7.5 HIGH 3.1 cna CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:H/A:N
References (1)
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