CVE-2025-62409: Envoyproxy Envoy

High severity, CVSS 7.5. EPSS: 0.5% chance of exploitation in the next 30 days.

Envoy is a cloud-native, open source edge and service proxy. Prior to 1.36.1, 1.35.5, 1.34.9, and 1.33.10, large requests and responses can potentially trigger TCP connection pool crashes due to flow control management in Envoy. It will happen when the connection is closing but upstream data is still coming, resulting in a buffer watermark callback nullptr reference. The vulnerability impacts TCP proxy and HTTP 1 & 2 mixed use cases based on ALPN. This vulnerability is fixed in 1.36.1, 1.35.5, 1.34.9, and 1.33.10.

Affected products

• Envoyproxy Envoy: before 1.33.11 (fixed in 1.33.11); from 1.34.0, before 1.34.9 (fixed in 1.34.9); from 1.35.0, before 1.35.5 (fixed in 1.35.5); version 1.36.0 only

Published 2025-10-16. Last modified 2026-10-09.