CVE-2026-73549

MEDIUM 5.3

Envoy - Incomplete fix for CVE-2026-26310: copyInternetAddressAndPort crashes on scoped IPv6 addresses in ORIGINAL_DST clusters

CVSS Score

5.3

EPSS Score

0.0%

EPSS Percentile

0th

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.

CWE	CWE-754
Vendor	envoyproxy
Product	envoy
Published	Sep 21, 2026

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CVSS v3 Breakdown

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

Attack Vector

Network

Attack Complexity

High

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Affected Versions

envoyproxy / envoy

< 1.36.10 >= 1.37.0, < 1.37.6 >= 1.38.0, < 1.38.4 >= 1.39.0, < 1.39.1

References

NVD ↗ CVE.org ↗ EPSS Data ↗