CVE-2025-62409

HIGH

Envoy < 1.36.1, 1.35.5, 1.34.9, 1.33.10 - Denial of Service via TCP Connection Pool Flow Control

Title source: llm
STIX 2.1

Description

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.

References (1)

Core 1
Core References

Scores

CVSS v3 7.5
EPSS 0.0042
EPSS Percentile 33.1%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CISA SSVC

Vulnrichment
Exploitation poc
Automatable yes
Technical Impact partial

Details

CWE
CWE-476
Status published
Products (2)
envoyproxy/envoy 1.36.0
envoyproxy/envoy < 1.33.11
Published Oct 16, 2025
Tracked Since Feb 18, 2026