# 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…

Source: https://junglewise.ai/threats/cve-2025-66220-envoy-is-a-high-performance-edge-middle-service-proxy-in-1-33-12  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2025-12-03  
License: CC BY 4.0 with a link back

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)](https://junglewise.ai/threats/technologies/github-com-envoyproxy-envoy). Vendors: [Go](https://junglewise.ai/threats/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

  ```sh
  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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