CVE-2026-13773
MediumCVSS 6.0Exploitation Probability (EPSS)
High risk87th percentile - higher than 87% of all known CVEs
Summary
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.
Risk Assessment
The risk is that an attacker can chain this SSRF with the IBM ORB getUserException class-instantiation flaw to achieve remote code execution on the calling JVM, leading to full server compromise and potential data breach.
Recommendation
Immediately upgrade IBM WebSphere Extreme Scale to version 8.6.1.7 or later, implement deserialization filtering for ObjectInputStream in WAS applications, and restrict IIOP traffic to trusted hosts.
Other vulnerabilities in IBM WebSphere Extreme Scale
See all- CVE-2026-9002Medium
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.
- CVE-2026-13772High
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.
- CVE-2026-13759High
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.
Original NVD description (English source)
IBM WebSphere Extreme Scale 8.6.1.0 through 8.6.1.6 Approximately 50 generated CORBA stub classes in WebSphere eXtreme Scale's ogclient.jar call ORB.string_to_object() on an attacker-controlled IOR string during Java deserialization, turning any unfiltered ObjectInputStream sink in WAS into outbound IIOP SSRF to an attacker-chosen host; when chained with the IBM ORB's getUserException class-instantiation flaw (WAS-26), this SSRF escalates to remote code execution on the calling JVM.