CVE-2026-15328 in WebSphere Application Server
Summary
by MITRE • 07/29/2026
IBM WebSphere Application Server 9.0, and 8.5 and IBM WebSphere Application Server - Liberty 17.0.0.3 through 26.0.0.7 is vulnerable to HTTP request smuggling.
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Analysis
by VulDB Data Team • 07/29/2026
IBM WebSphere Application Server versions 9.0, 8.5, and Liberty versions 17.0.0.3 through 26.0.0.7 contain a critical vulnerability that allows attackers to perform HTTP request smuggling attacks. This flaw exists in the server's handling of HTTP requests and responses, specifically in how it processes and forwards requests between client and backend servers. The vulnerability stems from improper parsing of HTTP headers and connection management that enables an attacker to manipulate the request flow and potentially bypass security controls.
The technical implementation of this vulnerability involves the server's inability to properly distinguish between legitimate HTTP requests and maliciously crafted sequences designed to exploit ambiguities in HTTP protocol handling. Attackers can construct specially formatted requests that cause the server to forward different requests to backend applications, creating opportunities for session hijacking, cross-site scripting, and data leakage. This behavior aligns with CWE-444, which describes improper request handling in web applications, and represents a significant deviation from proper HTTP protocol compliance.
The operational impact of this vulnerability is severe as it can enable attackers to perform various malicious activities including bypassing authentication mechanisms, accessing restricted resources, stealing sensitive session information, and conducting man-in-the-middle attacks. Organizations running these vulnerable versions of WebSphere Application Server face substantial risk of unauthorized access to their applications and data repositories. The vulnerability particularly affects environments where WebSphere serves as a reverse proxy or load balancer, as these configurations are most susceptible to the smuggling techniques.
Mitigation strategies should include immediate patching of affected systems to the latest supported versions of IBM WebSphere Application Server. Organizations should also implement network-level controls such as web application firewalls that can detect and block suspicious HTTP patterns. Additionally, security teams should review and strengthen their HTTP header validation processes, implement proper connection handling configurations, and conduct regular security assessments. The ATT&CK framework categorizes this vulnerability under technique T1190 for exploit public-facing application, making it a critical target for defensive measures in enterprise security postures. Organizations must also consider implementing monitoring solutions that can detect anomalous HTTP traffic patterns indicative of request smuggling attempts.