CVE-2025-54588

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

Published Sep 2, 2025 CVSS 3.1 · 7.5 High EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
EUVD EUVD EUVD-2025-26470 Envoy: Race condition in Dynamic Forward Proxy leads to use-after-free and segmentation faults
Github GHSA Github GHSA GHSA-g9vw-6pvx-7gmw Envoy: Race condition in Dynamic Forward Proxy leads to use-after-free and segmentation faults
History
Type Values Removed Values Added
CPEs cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:*
cpe:2.3:a:envoyproxy:envoy:1.35.0:*:*:*:*:*:*:*
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Envoyproxy
Envoyproxy envoy
Vendors & Products Envoyproxy
Envoyproxy envoy
Type Values Removed Values Added
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.
Title Envoy: Race condition in Dynamic Forward Proxy leads to use-after-free and segmentation faults
Weaknesses CWE-416
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Sep 3, 2025, 8:27 PM
Reserved
Jul 25, 2025, 4:19 PM
Status
Analyzed
Published
Sep 3, 2025, 12:15 AM
Modified
Jun 17, 2026, 9:40 AM
Severity
Important
Public date
Sep 3, 2025, 12:00 AM