CVE-2026-13759

IBM WebSphere eXtreme Scale is affected by Insecure Deserilization

Published Jun 30, 2026 CVSS 3.1 · 7.5 High EPSS < 1% KEV · Not listed
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

Remediation

Vendor Solution

We recommend customer to enable encryption. Please follow the link to enable encryption. https://www.ibm.com/docs/en/wxs/latest?topic=sydgies-securing-data-that-flows-between-extreme-scale-clients-servers-ssl-encryption. For extra security customer can enable JEP 290 global JVM deserialization filter (-Djdk.serialFilter) while starting catalog and container servers.JEP 290 is available from 8.0.8.5 onwards.

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Type Values Removed Values Added
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
Title IBM WebSphere eXtreme Scale is affected by Insecure Deserilization
First Time appeared Ibm
Ibm websphere Extreme Scale
Weaknesses CWE-502
CPEs cpe:2.3:a:ibm:websphere_extreme_scale:8.6.1.0:*:*:*:*:*:*:*
cpe:2.3:a:ibm:websphere_extreme_scale:8.6.1.6:*:*:*:*:*:*:*
Vendors & Products Ibm
Ibm websphere Extreme Scale
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
ibm
Published
Updated
Jul 3, 2026, 3:56 AM
Reserved
Jun 29, 2026, 6:10 PM
Status
Analyzed
Published
Jun 30, 2026, 8:17 PM
Modified
Oct 25, 2026, 9:10 PM