Answer in brief
CVE-2026-13759 records a High severity (CVSS 7.5) vulnerability in IBM WebSphere eXtreme Scale is affected by Insecure Deserilization. The current sources do not mark it as known exploited. The current feed maps IBM/WebSphere Extreme Scale (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 7.5. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps IBM/WebSphere Extreme Scale (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| IBM/WebSphere Extreme Scalegeneric | 8.6.1.0 | Not reported |
Published upstream
Jun 30, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Jul 3, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Jun 30, 2026
IBM WebSphere Extreme Scale 8.6.1.0 through 8.6.1.6 ships three ObjectInputStream subclasses (WsObjectInputStream, ObjectStreamPool$ReusableInputStream, ObjectInputStreamResolver) that install no JEP-290 class filter; when Coherence is on the classpath, multiple RCE gadget chains including RemoteConstructor.readResolve and PriorityQueue/ExtractorComparator are confirmed working, allowing a post-login attacker who can write a session attribute or a LAN-adjacent attacker on the grid replication wire to execute arbitrary code on peer WAS JVMs
Quoted source text, attributed separately from HOL analysis.
Answer in brief
CVE-2026-13759 records a High severity (CVSS 7.5) vulnerability in IBM WebSphere eXtreme Scale is affected by Insecure Deserilization. The current sources do not mark it as known exploited. The current feed maps IBM/WebSphere Extreme Scale (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 7.5. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps IBM/WebSphere Extreme Scale (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| IBM/WebSphere Extreme Scalegeneric | 8.6.1.0 | Not reported |
Published upstream
Jun 30, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Jul 3, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Jun 30, 2026
IBM WebSphere Extreme Scale 8.6.1.0 through 8.6.1.6 ships three ObjectInputStream subclasses (WsObjectInputStream, ObjectStreamPool$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
Quoted source text, attributed separately from HOL analysis.