CVE-2021-43826 HIGH

CVE-2021-43826: Crash when tunneling TCP over HTTP in Envoy

Vendor Envoyproxy
Product envoy
Weakness CWE-416
Published February 22, 2022
Last update April 23, 2025

CVSS base score

7.5/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Confidentiality None
Integrity None

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

What the vulnerability does

01Description

Envoy is an open source edge and service proxy, designed for cloud-native applications. In affected versions of Envoy a crash occurs when configured for :ref:`upstream tunneling <envoy_v3_api_field_extensions.filters.network.tcp_proxy.v3.TcpProxy.tunneling_config>` and the downstream connection disconnects while the the upstream connection or http/2 stream is still being established. There are no workarounds for this issue. Users are advised to upgrade.

Key dates

02Disclosure timeline

February 22, 2022 CVE published
April 23, 2025 Record updated