CVE-2026-11722 in WebSphere Application Server
Summary
by MITRE • 09/18/2026
IBM WebSphere Application Server and WebSphere Application Server Liberty are affected by an HTTP request smuggling vulnerability.
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Analysis
by VulDB Data Team • 09/18/2026
The identified security flaw within IBM WebSphere Application Server and WebSphere Application Server Liberty represents a critical class of vulnerabilities known as HTTP Request Smuggling, formally categorized under CWE-440 in the Common Weakness Enumeration taxonomy. This type of vulnerability arises from inconsistencies in how different layers of an application infrastructure interpret or parse HTTP request headers, specifically those related to message framing such as Content-Length and Transfer-Encoding. When a front-end proxy server and the back-end application server disagree on which header takes precedence for determining the boundaries of an HTTP request, it creates a state desynchronization that attackers can exploit to inject malicious requests into the stream intended for other users or internal services.
In this specific instance involving IBM WebSphere components, the vulnerability likely stems from improper validation or parsing logic within the HTTP protocol handler. An attacker could craft a specially crafted HTTP request containing conflicting headers, such as setting both Content-Length and Transfer-Encoding: chunked in a way that exploits the ambiguity defined by RFC 7230. For example, an attacker might send a request where the front-end proxy interprets the message length based on one header while the back-end WebSphere server processes it using another. This discrepancy allows the malicious payload to be smuggled into subsequent legitimate requests or processed as a separate command entirely, bypassing standard security controls that rely on clear request boundaries.
The operational impact of this vulnerability is severe and multifaceted. It enables attackers to perform session hijacking by stealing authentication cookies from other users whose requests are delayed behind the smuggled malicious traffic. Furthermore, it can lead to cache poisoning if a reverse proxy caches responses based on the smuggled content, serving poisoned data to subsequent victims. In more advanced scenarios, this flaw facilitates cross-site scripting (XSS) attacks or server-side request forgery (SSRF), allowing attackers to interact with internal network resources that are otherwise inaccessible from the public internet. The vulnerability aligns with MITRE ATT&CK technique T1071, Application Layer Protocol: Web Protocols, as it involves manipulating standard web traffic patterns to evade detection and achieve unauthorized access or data exfiltration.
Mitigation strategies for this issue require a multi-layered approach focusing on configuration hardening and patch management. The primary remediation is to apply the latest security patches provided by IBM that address the parsing logic flaws in WebSphere Application Server and Liberty profiles. Administrators should also ensure consistent HTTP header handling across all proxy layers; if possible, configure front-end proxies to strip or normalize conflicting headers before forwarding requests to the back end. Enforcing strict input validation on incoming requests and disabling unnecessary HTTP methods can further reduce the attack surface. Additionally, deploying a Web Application Firewall with rules specifically designed to detect request smuggling patterns provides an essential layer of defense in depth against exploitation attempts targeting this vulnerability class.