Uncaught Exception in envoy - CVE-2021-28683
Published: April 16, 2021 / Updated: August 26, 2026
Vulnerability identifier: #VU145851
CSH Severity: Medium
CVSS v4: 8.7 [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]
CVE-ID: CVE-2021-28683
CWE-ID: CWE-248
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to improper handling of unknown TLS alert codes in the TLS alert processing logic when processing a peer-supplied TLS alert. A remote attacker can send a TLS alert with an unknown code to cause a denial of service.
Affected software
envoy
How to mitigate CVE-2021-28683
Install security update from vendor's website.
envoy - addressed in versions 1.16.3, 1.17.2, 1.18.0