CVE-2026-13759 – IBM WebSphere eXtreme Scale is affected by Insecure Deserilization

CVE ID :CVE-2026-13759

Published : June 30, 2026, 7:24 p.m. | 22 minutes ago

Description :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

Severity: 7.5 | HIGH

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