CVE-2025-66220

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 v3.1 Score

5.0

MEDIUM

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

Weakness Type (CWE)

CWE-170 CWE-170

Affected Products

Vendor	Product	Versions
envoyproxy	envoy	< 1.33.13
envoyproxy	envoy	1.34.0 — 1.34.11
envoyproxy	envoy	1.35.0 — 1.35.7
envoyproxy	envoy	1.36.0 — 1.36.3

References

Advisories & Patches

https://github.com/envoyproxy/envoy/security/advisories/GHSA-rwjg-c3h2-f57p

Exploits

https://github.com/envoyproxy/envoy/security/advisories/GHSA-rwjg-c3h2-f57p

Frequently Asked Questions

What is CVE-2025-66220? +

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. It has a CVSS v3.1 base score of 5.0 (MEDIUM).

How severe is CVE-2025-66220? +

CVE-2025-66220 has a CVSS v3.1 score of 5.0 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

What products are affected by CVE-2025-66220? +

CVE-2025-66220 affects products from envoyproxy, specifically: envoy. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-66220? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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