CVE-2026-13759

EUVD-2026-40388
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
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
ibmCNA
7.5 HIGH
NETWORK
HIGH
LOW
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Base Score
CVSS 3.x
EPSS Score
Percentile: Unknown
Early Detection
Affected products identified ahead of NVD analysis through intelligence sources.
VendorProductVersionSource
ibmwebsphere_extreme_scale
8.6.1.0 ≤
𝑥
≤ 8.6.1.6
CNA
Common Weakness Enumeration
References
https://www.ibm.com/support/pages/node/7278595