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…

CVE-2025-66220 · Severity: medium · CVSS 5 · Published 2025-12-03

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.

Technologies: github.com/envoyproxy/envoy (Go). Vendors: Go.

Quick answers

Is CVE-2025-66220 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2025-66220 being exploited in the wild.
How severe is CVE-2025-66220?
Medium severity, with a CVSS score of 5, published 3 December 2025.
Which products and versions are affected?
github.com/envoyproxy/envoy (Go) SEMVER:introduced=1.36.0,fixed=1.36.3.
Is there a fix for CVE-2025-66220?
Yes. github.com/envoyproxy/envoy (Go): upgrade to 1.36.3 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
Am I affected by CVE-2025-66220?
Check whether you run github.com/envoyproxy/envoy (Go) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • github.com/envoyproxy/envoy (Go): upgrade to 1.36.3 or later
    go get github.com/envoyproxy/envoy@v1.36.3

Affected products

  • github.com/envoyproxy/envoy (Go) SEMVER:introduced=1.36.0,fixed=1.36.3

Identifiers

  • CVE-2025-66220
  • GHSA-rwjg-c3h2-f57p

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