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CVE-2026-73549

5.3 · MEDIUM

Envoy is an open source edge and service proxy designed for cloud-native applications.

Published Sep 21, 2026envoyproxyCWE-754EPSS 0.62%

Overview

CVE-2026-73549 is a medium-severity vulnerability affecting envoyproxy envoy. It was published on September 21, 2026 and has a CVSS 3.1 base score of 5.3 (MEDIUM).

This vulnerability has a CVSS 3.1 base score of 5.3, rated MEDIUM. It can be exploited remotely over the network. Some level of privileges is required for exploitation.

Technical description

Envoy is an open source edge and service proxy designed for cloud-native applications. Prior to 1.36.10, 1.37.6, 1.38.4, and 1.39.1, Envoy's Utility::copyInternetAddressAndPort and QUIC client-address paths reconstruct scoped IPv6 addresses through addressAsString and Ipv6Instance. The string includes a percent scope identifier that inet_pton cannot parse, causing an exception or abort. Kernel-provided scoped IPv6 destinations in ORIGINAL_DST transparent-proxy deployments, and affected QUIC connection paths, can therefore terminate the process. The relevant scope boundary is that the HTTP use_http_header override rejects scoped addresses earlier; the advisory's crash path requires a kernel-provided original destination or the affected QUIC path. This issue is fixed in versions 1.36.10, 1.37.6, 1.38.4, and 1.39.1.

Remediation

Check the references section for vendor advisories and patches from envoyproxy. Update envoy to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

Affected products

VendorProductVersionsStatus
envoyproxyenvoy>= 0, < 1.36.10Affected

References

GitHubgithub.com/envoyproxy/envoy/commit/109e5a5b08ad10d99074cefd55a747a16ee64da7GitHubgithub.com/envoyproxy/envoy/commit/59b1744a6cb62746db418ac06fc5e359fd25fdb7GitHubgithub.com/envoyproxy/envoy/commit/6e39f4c94deff7a60d382c2d95883e0ea49ff691GitHubgithub.com/envoyproxy/envoy/commit/ab2dca2d65b079768230a7c3d825afeefa330215GitHubgithub.com/envoyproxy/envoy/releases/tag/v1.36.10GitHubgithub.com/envoyproxy/envoy/releases/tag/v1.37.6GitHubgithub.com/envoyproxy/envoy/releases/tag/v1.38.4GitHubgithub.com/envoyproxy/envoy/releases/tag/v1.39.1GitHubgithub.com/envoyproxy/envoy/security/advisories/GHSA-jp5f-qr64-c9vw

How CyberStrike helps

Frequently asked questions

What is CVE-2026-73549?

CVE-2026-73549 is a medium-severity vulnerability affecting envoyproxy envoy. It was published on September 21, 2026 and has a CVSS 3.1 base score of 5.3 (MEDIUM).

How severe is CVE-2026-73549?

This vulnerability has a CVSS 3.1 base score of 5.3, rated MEDIUM. It can be exploited remotely over the network. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2026-73549?

Check the references section for vendor advisories and patches from envoyproxy. Update envoy to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-73549?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-73549 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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