CVE-2026-13759: CWE-502 Deserialization of Untrusted Data in IBM WebSphere Extreme Scale
IBM WebSphere Extreme Scale 8.6.1.0 through 8.6.1.6 ships three ObjectInputStream subclasses (WsObjectInputStream, ObjectStreamPool$ReusableInputStream, ObjectInputStreamResolver) that install no JEP-290 class filter; when Coherence is on the classpath, multiple RCE gadget chains including RemoteConstructor.readResolve and PriorityQueue/ExtractorComparator are confirmed working, allowing a post-login attacker who can write a session attribute or a LAN-adjacent attacker on the grid replication wire to execute arbitrary code on peer WAS JVMs
AI Analysis
Technical Summary
IBM WebSphere Extreme Scale 8.6.1.0 through 8.6.1.6 includes three ObjectInputStream subclasses (WsObjectInputStream, ObjectStreamPool$ReusableInputStream, ObjectInputStreamResolver) that do not implement JEP-290 class filtering. When Coherence is present on the classpath, multiple remote code execution gadget chains are confirmed, including RemoteConstructor.readResolve and PriorityQueue/ExtractorComparator. This enables attackers who have post-login access and can write session attributes, or attackers on the LAN grid replication wire, to execute arbitrary code on peer WebSphere Application Server JVMs.
Potential Impact
Successful exploitation allows arbitrary code execution on peer JVMs running IBM WebSphere Extreme Scale, potentially compromising confidentiality, integrity, and availability of affected systems. The vulnerability requires either post-login access with the ability to write session attributes or LAN adjacency on the grid replication network. This can lead to full system compromise of the affected application servers.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. No official fix or temporary workaround has been published at this time. Monitor IBM security advisories for updates and apply patches promptly once available. Until then, restrict access to the affected systems and limit the ability to write session attributes or access the grid replication network to trusted users only.
CVE-2026-13759: CWE-502 Deserialization of Untrusted Data in IBM WebSphere Extreme Scale
Description
IBM WebSphere Extreme Scale 8.6.1.0 through 8.6.1.6 ships three ObjectInputStream subclasses (WsObjectInputStream, ObjectStreamPool$ReusableInputStream, ObjectInputStreamResolver) that install no JEP-290 class filter; when Coherence is on the classpath, multiple RCE gadget chains including RemoteConstructor.readResolve and PriorityQueue/ExtractorComparator are confirmed working, allowing a post-login attacker who can write a session attribute or a LAN-adjacent attacker on the grid replication wire to execute arbitrary code on peer WAS JVMs
CVSS v3.1
Score 7.5high
Affected software
pkg:maven/com.ibm.websphere/websphere_extreme_scalecpe:2.3:a:ibm:websphere_extreme_scale:8.6.1.0:*:*:*:*:*:*:*cpe:2.3:a:ibm:websphere_extreme_scale:8.6.1.6:*:*:*:*:*:*:*Run on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
IBM WebSphere Extreme Scale 8.6.1.0 through 8.6.1.6 includes three ObjectInputStream subclasses (WsObjectInputStream, ObjectStreamPool$ReusableInputStream, ObjectInputStreamResolver) that do not implement JEP-290 class filtering. When Coherence is present on the classpath, multiple remote code execution gadget chains are confirmed, including RemoteConstructor.readResolve and PriorityQueue/ExtractorComparator. This enables attackers who have post-login access and can write session attributes, or attackers on the LAN grid replication wire, to execute arbitrary code on peer WebSphere Application Server JVMs.
Potential Impact
Successful exploitation allows arbitrary code execution on peer JVMs running IBM WebSphere Extreme Scale, potentially compromising confidentiality, integrity, and availability of affected systems. The vulnerability requires either post-login access with the ability to write session attributes or LAN adjacency on the grid replication network. This can lead to full system compromise of the affected application servers.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. No official fix or temporary workaround has been published at this time. Monitor IBM security advisories for updates and apply patches promptly once available. Until then, restrict access to the affected systems and limit the ability to write session attributes or access the grid replication network to trusted users only.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- ibm
- Date Reserved
- 2026-06-29T18:10:36.156Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a441ac027e9c7971948ab59
Added to database: 06/30/2026, 19:36:32 UTC
Last enriched: 07/08/2026, 11:37:25 UTC
Last updated: 08/13/2026, 12:41:08 UTC
Views: 63
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