CVE-2026-101117

IBM WebSphere Extreme Scale 8.6.1.0 through 8.6.1.6 contains approximately 50 generated CORBA stub classes in ogclient.jar that call ORB.string_to_object() on an attacker-controlled IOR string during Java deserialization. This turns any unfiltered ObjectInputStream sink in WAS into outbound IIOP SSRF to an attacker-chosen host.

IBM WebSphere Extreme Scale versions 8.6.1.0 through 8.6.1.6 contain a denial-of-service vulnerability due to improper validation in the XDF decoder. The application processes deeply nested Protocol Buffers messages and attacker-controlled length prefixes without sufficient bounds checking, which may lead to a StackOverflowError or OutOfMemoryError.

IBM WebSphere Extreme Scale 8.6.1.0 through 8.6.1.6 contains a vulnerability in the Object Query Language engine that resolves attacker-supplied class names via Class.forName() and invokes their constructors without an allow-list at three distinct sinks (SELECT NEW, enum literals, and reflection-based comparators). An authenticated remote attacker who can influence an application-built OQL query string can execute arbitrary constructors on the WAS JVM, and a SELECT DISTINCT variant using planted grid values triggers the same gadget post-deserialization in a manner that bypasses JEP-290 serialization filters across grid node boundaries.

IBM WebSphere Extreme Scale 8.6.1.0 through 8.6.1.6 ships three ObjectInputStream subclasses (WsObjectInputStream, ObjectStreamPool$ReusableInputStream, ObjectInputStreamResolver) that install no JEP-290 class filter; when Coherence is on the classpath, multiple RCE gadget chains including RemoteConstructor.readResolve and PriorityQueue/ExtractorComparator are confirmed working, allowing a post-login attacker who can write a session attribute or a LAN-adjacent attacker on the grid replication wire to execute arbitrary code on peer WAS JVMs.