Improper certificate validation in envoy - CVE-2025-66220
Published: December 3, 2025
Vulnerability identifier: #VU119112
CSH Severity: Low
CVSS v4: 2.3 [CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2025-66220
CWE-ID: CWE-295
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to impersonate other users.
The vulnerability exists due to incorrect processing of client certificates with an embedded null byte (\0) inside an OTHERNAME SAN value. A remote attacker who can obtain a trusted client certificate can impersonate a matched identity and bypass TLS-based authorization checks.
Affected software
envoy
How to mitigate CVE-2025-66220
Install updates from vendor's website.
envoy - addressed in versions 1.33.13, 1.34.11, 1.35.7, 1.36.3