CVE-2026-13759: IBM WebSphere Extreme Scale · Deserialization of Untrusted Data
Affects IBM WebSphere Extreme ScaleSource CVE Database V5
Not known to be exploited · CVSS 7.5 High.
Data as of 12 Nov 2026, 23:24 UTC
- EPSS
- 0.5% chance of exploitation in 30 days – higher than 46% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 30 Jun 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 13 Nov 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| IBMWebSphere Extreme Scale | Affected
| Fixed in– |
Mavencom.ibm.websphere/websphere_extreme_scalepkg:maven/com.ibm.websphere/websphere_extreme_scaleOther threats | Affected
| Fixed in– |
CPE configurations (2)
cpe:2.3:a:ibm:websphere_extreme_scale:8.6.1.0:*:*:*:*:*:*:*cpe:2.3:a:ibm:websphere_extreme_scale:8.6.1.6:*:*:*:*:*:*:*
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
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.
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