High severity · published Dec 3, 2025
CVE-2025-66220
Envoy’s TLS certificate matcher for `match_typed_subject_alt_names` may incorrectly treat certificates containing an embedded null byte
7.1
CVSS
0.2%
EPSS
No
On KEV
Description
Envoy is a high-performance edge/middle/service proxy. In 1.33.12, 1.34.10, 1.35.6, 1.36.2, and earlier, Envoy’s mTLS certificate matcher for match_typed_subject_alt_names may incorrectly treat certificates containing an embedded null byte (\0) inside an OTHERNAME SAN value as valid matches.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
High
Integrity
Low
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.2% · higher than 6% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
EN
envoy · envoyproxy
>= 1.36.0, <= 1.36.2; >= 1.35.0, <= 1.35.6; >= 1.34.0, <= 1.34.10; <= 1.33.12 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2025-66220
CVE.org
https://www.cve.org/CVERecord?id=CVE-2025-66220
Exploit
https://github.com/envoyproxy/envoy/security/advisories/GHSA-rwjg-c3h2-f57p
More from envoy
9.8
CVE-2026-111497
Out-of-Bounds Write in Google Brotli Decoder
7.5
CVE-2023-44487
HTTP/2 Rapid Reset Attack Vulnerability
10.0
CVE-2019-9901
Envoy 1.9.0 and before does not normalize HTTP URL paths
9.8
CVE-2023-35941
Envoy is an open source edge and service proxy designed for cloud-native applications
9.8
CVE-2023-27488
Envoy is an open source edge and service proxy designed for cloud-native applications