Use-after-free in envoy - CVE-2021-43826
Published: February 22, 2022 / Updated: August 26, 2026
Vulnerability identifier: #VU145848
CSH Severity: Medium
CVSS v4: 5.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N]
CVE-ID: CVE-2021-43826
CWE-ID: CWE-416
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to affect integrity and availability.
The vulnerability exists due to use-after-free in the TCP-over-HTTP tunneling functionality when handling a downstream disconnect during upstream connection establishment. A remote attacker can trigger a downstream disconnect condition to affect integrity and availability.
User interaction is required.
Affected software
envoy
How to mitigate CVE-2021-43826
Install security update from vendor's website.
envoy - addressed in versions 1.18.6, 1.19.3, 1.20.2, 1.21.1