CVE-2026-15396Network attack vectorHinoki check available

Cache poisoning via malformed Transfer-Encoding parsing

Published Sep 14, 2026 · Updated Sep 14, 2026

HTTP request smuggling in IBM WebSphere Application Server 8.5 and 9.0 allows remote attackers to manipulate downstream HTTP processing. Its HTTP parser handles crafted Transfer-Encoding request headers inconsistently, allowing a front end and the server to disagree about request boundaries. No authentication or user interaction is required; successful requests can poison a web cache, bypass web application firewall controls, or inject cross-site scripting content.

CVSS severity6.5
Medium
EPSS probability0.25%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

HTTP request smuggling in IBM WebSphere Application Server 8.5 and 9.0 allows remote attackers to manipulate downstream HTTP processing. Its HTTP parser handles crafted Transfer-Encoding request headers inconsistently, allowing a front end and the server to disagree about request boundaries. No authentication or user interaction is required; successful requests can poison a web cache, bypass web application firewall controls, or inject cross-site scripting content.

The record

CVE
CVE-2026-15396
Published
Sep 14, 2026
Updated
Sep 14, 2026
Vendor
IBM
Product
IBM WebSphere Application Server
Classifications
CWE-444, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 14, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 14, 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?

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  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

Published CVSS scores

6.5IBMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-444Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
T1190Exploit Public-Facing Application

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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