{"id":86912,"date":"2026-04-10T04:26:28","date_gmt":"2026-04-10T04:26:28","guid":{"rendered":""},"modified":"-0001-11-30T00:00:00","modified_gmt":"-0001-11-30T00:00:00","slug":"cve-2025-54588-use-after-free-vulnerability-in-envoy-s-dynamic-forward-proxy-implementation","status":"publish","type":"post","link":"https:\/\/www.ameeba.com\/blog\/cve-2025-54588-use-after-free-vulnerability-in-envoy-s-dynamic-forward-proxy-implementation\/","title":{"rendered":"CVE-2025-54588: Use-After-Free Vulnerability in Envoy’s Dynamic Forward Proxy Implementation<\/strong>"},"content":{"rendered":"

Overview<\/strong><\/p>\n

This report examines the CVE-2025-54588 vulnerability found in the open-source proxy and communication bus Envoy. This vulnerability, affecting versions 1.34.0 through 1.34.4 and 1.35.0, could potentially lead to system compromise or data leakage. For organizations leveraging Envoy for service-oriented architectures, understanding and mitigating this vulnerability is crucial for maintaining system integrity and data security.<\/p>\n

Vulnerability Summary<\/strong><\/p>\n

CVE ID: CVE-2025-54588
\nSeverity: High (7.5 CVSS)
\nAttack Vector: Network
\nPrivileges Required: None
\nUser Interaction: None
\nImpact: Potential system compromise or data leakage<\/p>\n

Affected Products<\/strong><\/p>\n

Product | Affected Versions<\/p>\n

Envoy | 1.34.0 – 1.34.4, 1.35.0<\/p>\n

How the Exploit Works<\/strong><\/p>\n

The vulnerability resides in Envoy’s Dynamic Forward Proxy implementation, specifically within the DNS cache. It is a use-after-free (UAF) vulnerability that can cause abnormal process termination. This condition occurs when a completion callback for a DNS resolution triggers new DNS resolutions or removes existing pending resolutions. The vulnerability could be exploited when the 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.<\/p>\n

Conceptual Example Code<\/strong><\/p>\n

While exact exploitation methods may vary, the following conceptual HTTP request might be used by an attacker exploiting this vulnerability. In this scenario, the Host header is manipulated:<\/p>\n

GET \/some_endpoint HTTP\/1.1\nHost: target.example.com\nX-Forwarded-Host: malicious.example.com\n...<\/code><\/pre>\n
In this example, the attacker attempts to manipulate the Host header between the Dynamic Forwarding Filter and Router filters, potentially triggering the UAF vulnerability in the DNS cache and causing the Envoy process to terminate abnormally.<\/p>\n
Mitigation Guidance<\/strong><\/p>\n
The immediate mitigation for this vulnerability is to upgrade to versions 1.34.5 or 1.35.1, where the issue has been resolved. If upgrading isn’t feasible, organizations can set the `envoy.reloadable_features.dfp_cluster_resolves_hosts` runtime flag to false as a workaround. Alternatively, deploying a Web Application Firewall (WAF) or Intrusion Detection System (IDS) can offer temporary mitigation against potential exploits.<\/p>\n","protected":false},"excerpt":{"rendered":"
Overview This report examines the CVE-2025-54588 vulnerability found in the open-source proxy and communication bus Envoy. This vulnerability, affecting versions 1.34.0 through 1.34.4 and 1.35.0, could potentially lead to system compromise or data leakage. For organizations leveraging Envoy for service-oriented architectures, understanding and mitigating this vulnerability is crucial for maintaining system integrity and data security. […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"om_disable_all_campaigns":false,"_monsterinsights_skip_tracking":false,"footnotes":""},"categories":[],"tags":[],"vendor":[],"product":[],"attack_vector":[],"asset_type":[],"severity":[],"exploit_status":[],"class_list":["post-86912","post","type-post","status-publish","format-standard","hentry"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t