CVE-2026-13759CWE-502

IBM WebSphere eXtreme Scale is affected by Insecure Deserilization

High · published June 30, 2026

CVSS v3.1
7.5
EPSS
1%
Percentile
45.0
In the wild
Unconfirmed
What it is

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

The record
Technical detail
CVSS v3.1
7.5 · HIGH
Vector
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
CVSS v4.0
Not supplied
EPSS
0.00546 · 45.0th percentile
Weakness
CWE-502 · Deserialization of Untrusted Data
Published
2026-06-30T19:24Z
EPSS history
Timeline
  • 30 JUN 19:24Z
    IBM WebSphere eXtreme Scale is affected by Insecure Deserilization
    cvelistv5