CVE-2026-8400 in WebSphere Application Server
Summary
by MITRE • 08/05/2026
IBM WebSphere Application Server 8.5, and 9.0 and IBM WebSphere Application Server - Liberty Continuous delivery has a flaw in the ORB component in IBM SDK, Java Technology Edition, may allow a malicious IIOP server to induce loading and instantation of arbitrary classes.
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Analysis
by VulDB Data Team • 08/05/2026
The vulnerability resides within the Object Request Broker (ORB) component of IBM WebSphere Application Server versions 8.5 and 9.0, as well as the Liberty profile's continuous delivery functionality. This flaw exists in the IBM SDK, Java Technology Edition implementation and represents a critical security weakness that can be exploited through the Internet Inter-Orb Protocol (IIOP) communication channel. The vulnerability stems from insufficient validation of class loading requests initiated by remote IIOP servers, allowing malicious actors to manipulate the system into loading and instantiating arbitrary Java classes from untrusted sources.
The technical implementation flaw manifests when the ORB component processes incoming IIOP requests without proper sanitization of class references or object serialization parameters. This weakness creates a path for remote code execution through deserialization attacks, where an attacker can craft malicious IIOP messages that trigger the loading of specially crafted class files. The vulnerability aligns with CWE-502 which describes "Deserialization of Untrusted Data" and represents a specific instance of insecure deserialization in Java applications. Attackers can leverage this flaw to execute arbitrary code on the target system with the privileges of the WebSphere application server process, potentially leading to complete system compromise.
The operational impact of this vulnerability is severe for organizations running affected IBM WebSphere instances, particularly those exposed to untrusted network environments or lacking proper network segmentation. The attack surface expands significantly when considering that IIOP is typically used for distributed object communication in enterprise applications, making it a common target for attackers seeking to exploit Java-based middleware systems. Organizations may experience unauthorized access to sensitive data, system compromise, and potential lateral movement within their network infrastructure if the application server has elevated privileges or access to critical internal resources.
Mitigation strategies should include immediate patching of affected IBM WebSphere versions through official IBM security updates that address the ORB component vulnerabilities. Network segmentation practices should be implemented to restrict IIOP traffic to trusted sources only, while firewall rules should be configured to block unnecessary IIOP ports. Organizations should also consider disabling IIOP functionality entirely if it is not required for their applications, as this removes the attack surface entirely. Additionally, implementing runtime application self-protection measures and monitoring for unusual class loading activities can help detect potential exploitation attempts. The vulnerability's classification under ATT&CK technique T1059.007 for "Command and Scripting Interpreter: PowerShell" and T1203 for "Exploitation for Client Execution" indicates that attackers may use this flaw as part of broader attack chains targeting enterprise Java applications.