{"id":86921,"date":"2026-04-11T06:26:57","date_gmt":"2026-04-11T06:26:57","guid":{"rendered":""},"modified":"-0001-11-30T00:00:00","modified_gmt":"-0001-11-30T00:00:00","slug":"cve-2025-58056-netty-http-request-smuggling-vulnerability","status":"publish","type":"post","link":"https:\/\/www.ameeba.com\/blog\/cve-2025-58056-netty-http-request-smuggling-vulnerability\/","title":{"rendered":"CVE-2025-58056: Netty HTTP Request Smuggling Vulnerability<\/strong>"},"content":{"rendered":"

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

This report focuses on a critical vulnerability, CVE-2025-58056, found in certain versions of the Netty network application framework. This vulnerability is of significance due to Netty’s wide usage in the development of protocol servers and clients, and hence, it has the potential to affect a large number of network applications globally. The vulnerability allows attackers to conduct request smuggling attacks, which can lead to system compromise or data leakage.<\/p>\n

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

CVE ID: CVE-2025-58056
\nSeverity: High (7.5 CVSS Score)
\nAttack Vector: Network
\nPrivileges Required: None
\nUser Interaction: None
\nImpact: System compromise or data leakage<\/p>\n

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

Product | Affected Versions<\/p>\n

Netty | 4.1.124.Final
\nNetty | 4.2.0.Alpha3 through 4.2.4.Final<\/p>\n

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

The exploit works by taking advantage of Netty’s incorrect handling of newline characters (LF) as a chunk-size line terminator. By crafting a request that reverse proxies parse as one request but Netty processes as two, attackers can perform request smuggling attacks. This discrepancy allows attackers to inject malicious content, which can lead to unauthorized system access or data exposure.<\/p>\n

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

Here is a conceptual example of how an HTTP request smuggling attack might be crafted:<\/p>\n

POST \/vulnerable\/endpoint HTTP\/1.1\nHost: target.example.com\nContent-Length: 83\nPOST \/internal\/endpoint HTTP\/1.1\nHost: target.example.com\nContent-Type: application\/json\n{ \"malicious_payload\": \"...\" }<\/code><\/pre>\n
In this example, the attacker is sending what appears to be a single HTTP request to a vulnerable proxy server. However, due to the LF parsing error, Netty sees this as two separate requests. The second request, containing the malicious payload, is then processed by the target server.<\/p>\n
Mitigation Guidance<\/strong><\/p>\n
To mitigate the vulnerability, users should update to versions 4.1.125.Final or 4.2.5.Final where the issue has been fixed. If patching is not immediately possible, deploying a Web Application Firewall (WAF) or an Intrusion Detection System (IDS) can serve as temporary mitigation.<\/p>\n","protected":false},"excerpt":{"rendered":"
Overview This report focuses on a critical vulnerability, CVE-2025-58056, found in certain versions of the Netty network application framework. This vulnerability is of significance due to Netty’s wide usage in the development of protocol servers and clients, and hence, it has the potential to affect a large number of network applications globally. The vulnerability allows […]<\/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-86921","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