CVE-2026-47692
MediumCVSS 4.8Exploitation Probability (EPSS)
Low risk12th percentile — higher than 12% of all known CVEs
Summary
A vulnerability in Envoy's PROXY Protocol v2 header generator allows TLVs to exceed the maximum length of 65535 bytes, causing a mismatch between written bytes and the length field, enabling byte smuggling in upstream requests.
Risk Assessment
An attacker could exploit this flaw to smuggle malicious data into upstream requests, potentially leading to data integrity breaches, security bypass, or further attack escalation.
Recommendation
Immediately upgrade Envoy to versions 1.35.13, 1.36.9, 1.37.5, or 1.38.3, depending on the branch in use. The update fixes the improper generation of PROXY Protocol v2 headers.
Original NVD description (English source)
Envoy is an open source edge and service proxy designed for cloud-native applications. From 1.34.0 until 1.35.13, 1.36.9, 1.37.5, and 1.38.3, PROXY Protocol v2 header generator emits TLVs beyond the maximum length of 65535 bytes, causing a mismatch between bytes written and the length field in the header. This can result in smuggled bytes on the upstream request. This vulnerability is fixed in 1.35.13, 1.36.9, 1.37.5, and 1.38.3.