IBM WebSphere Extreme Scale 8.6.1.08.6.1.6 RCE via ObjectInputStream (Coherence)
CVE-2026-13759 Published on June 30, 2026
IBM WebSphere eXtreme Scale is affected by Insecure Deserilization
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
Vulnerability Analysis
CVE-2026-13759 can be exploited with network access, and requires small amount of user privileges. This vulnerability is consided to have a high level of attack complexity. The potential impact of an exploit of this vulnerability is considered to be very high.
Weakness Type
What is a Marshaling, Unmarshaling Vulnerability?
The application deserializes untrusted data without sufficiently verifying that the resulting data will be valid.
CVE-2026-13759 has been classified to as a Marshaling, Unmarshaling vulnerability or weakness.
Products Associated with CVE-2026-13759
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Affected Versions
IBM WebSphere Extreme Scale:- Version 8.6.1.0, <= 8.6.1.6 is affected.