CVE-2026-13759

highCVSS 7.5covered by 1 sourcefirst seen 2026-06-30

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

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Exploitation outlook

Low exploitation risk0.30% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 22% of all EPSS-scored CVEs.

Advisory coverage (1)

highCVE-2026-13759: IBM WebSphere Extreme Scale 8.6.1.0 through 8.6.1.6 ships three ObjectInputStream subclasses (…nvd · 2026-06-30

External references

NVD record for CVE-2026-13759

CVE.org record

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