CVE-2026-73549

What it is

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.

At a glance

Exploitability

Can be exploited over the network with a low-privilege account. High risk of service disruption.

Exploit odds

0.6% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-09-21 20:17 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-10-05 14:09 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.6% in the next 30 days (EPSS).
• Severity: 5.3 MEDIUM (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2026-09-21 20:17 UTC

Last modified

2026-10-05 14:09 UTC

Exploit probability

0.6% · EPSS, next 30 days

Weakness

CWE-754

Record status

Analyzed

Affected

• Envoyproxy Envoy < 1.36.10
• Envoyproxy Envoy < 1.37.6
• Envoyproxy Envoy < 1.38.4
• Envoyproxy Envoy < 1.39.1

Attack profile CVSS 3.1 · 5.3

Attack vector

Network

Complexity

High

Privileges needed

Low

User interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2026-73549.md and follow it. Check whether this project is affected by CVE-2026-73549. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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