CVE-2026-15064 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 Response Smuggling due to improper handling of non-standard HTTP version tokens.
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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 vulnerability classified as HTTP Response Smuggling that stems from inadequate processing of non-standard HTTP version tokens within the server's request handling mechanism. This flaw exists in the HTTP protocol parsing logic where the application server fails to properly validate or sanitize HTTP version identifiers that do not conform to standard specifications. The vulnerability manifests when the server receives requests containing malformed or non-conforming HTTP version tokens, which can lead to inconsistent interpretation of request boundaries and response handling between different components within the server architecture.
The technical implementation of this vulnerability allows an attacker to manipulate HTTP headers and request parsing behavior by injecting specially crafted non-standard HTTP version tokens into incoming requests. When the WebSphere server processes these malformed requests, it creates ambiguity in how subsequent requests are handled, potentially allowing attackers to inject malicious responses or manipulate the flow of HTTP communication between client and server. This occurs because the application server's HTTP parser does not adequately distinguish between legitimate and malicious version specifications, leading to potential confusion in request boundary detection and response assembly processes.
The operational impact of this vulnerability extends beyond simple protocol parsing errors and can enable sophisticated attack scenarios including cache poisoning, session hijacking, and cross-site scripting exploitation. Attackers can leverage this weakness to manipulate how responses are cached or delivered to clients, potentially causing users to receive malicious content or enabling bypasses of security controls that depend on proper HTTP protocol handling. The vulnerability affects the fundamental integrity of HTTP communication within the server environment, creating opportunities for data exfiltration, service disruption, and unauthorized access to protected resources.
Security mitigations for this vulnerability should focus on implementing strict HTTP version validation controls and ensuring proper input sanitization of all incoming HTTP requests. Organizations should consider applying the latest security patches provided by IBM that address the specific HTTP version token handling issues within WebSphere Application Server implementations. Network-level protections including web application firewalls and HTTP protocol compliance checking can help detect and block malformed requests before they reach the vulnerable server components. Additionally, implementing proper logging and monitoring of HTTP request patterns can aid in identifying potential exploitation attempts and provide early detection capabilities for this class of vulnerability classified under CWE-1037 for improper handling of HTTP version tokens and potentially related to CWE-346 for origin validation failures in web applications.