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Vulnerability · Published Sep 2, 2025 · Assigned by GitHub_M

CVE-2025-54588Envoy: Race condition in Dynamic Forward Proxy leads to use-after-free and segmentation faults

High 7.5

In plain English

A high-severity use-after-free in envoy from envoyproxy. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 43% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)7.5High
Exploit odds (30 days)0.5%top 57.4% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

Envoy is an open source L7 proxy and communication bus designed for large modern service oriented architectures. Versions 1.34.0 through 1.34.4 and 1.35.0 contain a use-after-free (UAF) vulnerability in the DNS cache, causing abnormal process termination. The vulnerability is in Envoy's Dynamic Forward Proxy implementation, occurring when a completion callback for a DNS resolution triggers new DNS resolutions or removes existing pending resolutions. This condition may occur when the following conditions are met: dynamic Forwarding Filter is enabled, the `envoy.reloadable_features.dfp_cluster_resolves_hosts` runtime flag is enabled, and the Host header is modified between the Dynamic Forwarding Filter and Router filters. This issue is resolved in versions 1.34.5 and 1.35.1. To work around this issue, set the envoy.reloadable_features.dfp_cluster_resolves_hosts runtime flag to false.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Gogithub.com/envoyproxy/envoy1.35.1GHSA-g9vw-6pvx-7gmw
Gogithub.com/envoyproxy/envoy1.34.5GHSA-g9vw-6pvx-7gmw

Affected products (as reported)

VendorProductVersions
envoyproxy envoy >= 1.34.0, < 1.34.5>= 1.35.0, < 1.35.1

Weakness: CWE-416 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References