CVE-2025-62409 MEDIUM

CVE-2025-62409: Envoy allows large requests and responses to cause TCP connection pool crash

Vendor Envoyproxy
Product envoy
Weakness CWE-476
Published October 16, 2025
Last update October 16, 2025
View on NVD All CVEs

CVSS base score

6.6/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Confidentiality —
Integrity —

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

October 16, 2025 CVE published
October 16, 2025 Record updated