CVE-2026-8400Network attack vectorHinoki check available

Unauthenticated class instantiation via malicious IIOP server

Published Aug 5, 2026 · Updated Aug 5, 2026

Unsafe reflection in IBM WebSphere Application Server 8.5, 9.0, and Liberty Continuous delivery allows remote attackers to instantiate arbitrary classes. The IBM Java ORB allows a malicious IIOP server to induce class loading and instantiation, but IBM has not published the exact class-selection locus or validation failure. Exploitation requires unauthenticated network interaction with an attacker-controlled IIOP server, and selected constructors run in the affected server process.

CVSS severity8.1
High
EPSS probability0.27%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Unsafe reflection in IBM WebSphere Application Server 8.5, 9.0, and Liberty Continuous delivery allows remote attackers to instantiate arbitrary classes. The IBM Java ORB allows a malicious IIOP server to induce class loading and instantiation, but IBM has not published the exact class-selection locus or validation failure. Exploitation requires unauthenticated network interaction with an attacker-controlled IIOP server, and selected constructors run in the affected server process.

The record

CVE
CVE-2026-8400
Published
Aug 5, 2026
Updated
Aug 5, 2026
Vendor
IBM
Product
IBM WebSphere Application Server
Classifications
CWE-470, CAPEC-138, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 5, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=8.5
  2. Affected versionversion=9.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

IBM · IBM WebSphere Application Serverversion=8.5; version=9.0
IBM · IBM WebSphere Application Server Libertyversion=Continuous delivery

Published CVSS scores

9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
8.1IBMCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-470Use of Externally-Controlled Input to Select Classes or Code ('Unsafe Reflection')
CAPEC-138Reflection Injection
T1203Exploitation for Client Execution

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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