{"id":86247,"date":"2026-01-10T02:23:23","date_gmt":"2026-01-10T02:23:23","guid":{"rendered":""},"modified":"-0001-11-30T00:00:00","modified_gmt":"-0001-11-30T00:00:00","slug":"cve-2025-27820-apache-httpclient-psl-validation-logic-bug","status":"publish","type":"post","link":"https:\/\/www.ameeba.com\/blog\/cve-2025-27820-apache-httpclient-psl-validation-logic-bug\/","title":{"rendered":"CVE-2025-27820: Apache HttpClient PSL Validation Logic Bug<\/strong>"},"content":{"rendered":"

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

A critical vulnerability has been identified in Apache HttpClient 5.4.x. This vulnerability, classified under the CVE ID CVE-2025-27820, arises from a bug in the PSL (Public Suffix List) validation logic which disables domain checks, primarily affecting cookie management and hostname verification. This weakness could potentially lead to a system compromise or data leakage, making it a significant risk to organizations using the affected versions of Apache HttpClient.<\/p>\n

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

CVE ID: CVE-2025-27820
\nSeverity: High (CVSS: 7.5)
\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

Apache HttpClient | 5.4.0 to 5.4.2<\/p>\n

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

The exploitation of this vulnerability can occur when a malicious actor sends a specially crafted request to the server using the affected versions of Apache HttpClient. Due to the bug in the PSL validation logic, the software does not perform adequate domain checks. This flaw can be leveraged to manipulate cookie management and hostname verification, potentially leading to unauthorized access or extraction of sensitive data.<\/p>\n

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

Here is a conceptual example of how this vulnerability might be exploited:<\/p>\n

POST \/vulnerable\/endpoint HTTP\/1.1\nHost: target.example.com\nCookie: sessionid=malicious_cookie\n{\n\"malicious_payload\": \"...\"\n}<\/code><\/pre>\n
In this example, the attacker exploits the PSL validation logic bug to inject a malicious cookie into the HTTP request. Successful exploitation could compromise the system and potentially lead to data leakage.<\/p>\n
Mitigation Guidance<\/strong><\/p>\n
Users are advised to mitigate this vulnerability by applying the vendor patch as soon as possible. The Apache HttpClient team has released version 5.4.3, which resolves the identified bug. As a temporary mitigation measure, organizations can also use a Web Application Firewall (WAF) or an Intrusion Detection System (IDS) to detect and prevent exploitation attempts.<\/p>\n","protected":false},"excerpt":{"rendered":"
Overview A critical vulnerability has been identified in Apache HttpClient 5.4.x. This vulnerability, classified under the CVE ID CVE-2025-27820, arises from a bug in the PSL (Public Suffix List) validation logic which disables domain checks, primarily affecting cookie management and hostname verification. This weakness could potentially lead to a system compromise or data leakage, making […]<\/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-86247","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