Inconsistent interpretation of HTTP requests in IBM WebSphere Application Server and IBM WebSphere Application Server Liberty - CVE-2026-8646

Vulnerability identifier: #VU139055

CSH Severity: High

CVSS v4: 9.1 [CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-8646

CWE-ID: CWE-444

Exploitation vector: Remote access

Exploit availability: No public exploit available

The vulnerability allows a remote attacker to perform HTTP request smuggling attacks.

The vulnerability exists due to improper validation of HTTP requests. A remote attacker can send a specially crafted HTTP request to the server and smuggle arbitrary HTTP headers.

Successful exploitation of vulnerability may allow an attacker to poison HTTP cache and perform phishing attacks.

IBM WebSphere Application Server
IBM WebSphere Application Server Liberty
Voice Gateway
Jazz for Service Management
IBM SPSS Analytic Server
IBM Security Guardium Key Lifecycle Manager (GKLM)
IBM Tivoli System Automation Application Manager
IBM Tivoli Monitoring
IBM TXSeries for Multiplatforms
WebSphere Remote Server
IBM Rational ClearQuest
IBM Business Automation Workflow
PowerVM NovaLink
Tivoli Network Manager IP Edition
Cloud Pak for Applications
WebSphere Hybrid Edition
Enterprise Application Runtimes
Tivoli Composite Application Manager for Application Diagnostics
IBM OpenPages with Watson
CICS Transaction Gateway Desktop Edition
IBM Watson Explorer Analytical Components
IBM Watson Explorer Foundational Components

Install updates from vendor's website.

IBM WebSphere Application Server - addressed in versions 8.5.5.30, 9.0.5.29
IBM WebSphere Application Server Liberty - update to 26.0.0.7
Voice Gateway - addressed in versions 1.0.8.21, 1.0.8.29
PowerVM NovaLink - addressed in versions 2.2.1.1-260708, 2.3.3-260714
IBM Tivoli Monitoring - update to 6.3.0.7 Service Pack 22
IBM TXSeries for Multiplatforms - update to 11.1.0.0 ifix22
IBM Watson Explorer Analytical Components - update to 12.0.3.22 PH71585
IBM Watson Explorer Foundational Components - update to 12.0.3.22 PH71585

• https://www.ibm.com/support/pages/node/7276579

• Inconsistent interpretation of HTTP requests in IBM WebSphere Application Server and IBM WebSphere Application Server - Liberty
• Multiple vulnerabilities in IBM PowerVM Novalink
• Multiple vulnerabilities in IBM Tivoli System Automation Application Manager
• Multiple vulnerabilities in IBM WebSphere Remote Server
• Multiple vulnerabilities in CICS Transaction Gateway Desktop Edition
• Multiple vulnerabilities in IBM SPSS Analytic Server
• Multiple vulnerabilities in IBM Rational ClearQuest
• Multiple vulnerabilities in IBM Watson Explorer
• Multiple vulnerabilities in IBM TXSeries for Multiplatforms
• Multiple vulnerabilities in IBM Voice Gateway
• Multiple vulnerabilities in IBM Jazz for Service Management
• Multiple vulnerabilities in IBM Tivoli Composite Application Manager for Application Diagnostics
• Multiple vulnerabilities in IBM WebSphere Hybrid Edition
• Multiple vulnerabilities in IBM Cloud Pak for Applications
• Multiple vulnerabilities in IBM Tivoli Network Manager IP Edition
• Multiple vulnerabilities in IBM Enterprise Application Runtimes
• Multiple vulnerabilities in IBM Tivoli Monitoring
• Multiple vulnerabilities in IBM Guardium Key Lifecycle Manager (GKLM)
• Multiple vulnerabilities in IBM Buinses Automation Workflow
• Multiple vulnerabilities in IBM OpenPages