IBM WebSphere App Server 9.0 HTTP Request Smuggling via Transfer-Encoding
CVE-2026-15634 Published on September 14, 2026
IBM WebSphere Application Server prior to 9.0.5.29 and 8.5.5.31 are affected by multiple vulnerabilities
IBM WebSphere Application Server 9.0, and 8.5 and IBM WebSphere Application Server - Liberty are vulnerable to HTTP request smuggling, caused by improper parsing of the HTTP transfer-encoding request header. By sending a specially crafted HTTP transfer-encoding request header, an attacker could exploit this vulnerability to poison the web cache, bypass web application firewall protection, and conduct XSS attacks.
Vulnerability Analysis
CVE-2026-15634 is exploitable with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have a small impact on confidentiality and integrity, and no impact on availability.
Weakness Type
What is a HTTP Request Smuggling Vulnerability?
When malformed or abnormal HTTP requests are interpreted by one or more entities in the data flow between the user and the web server, such as a proxy or firewall, they can be interpreted inconsistently, allowing the attacker to "smuggle" a request to one device without the other device being aware of it.
CVE-2026-15634 has been classified to as a HTTP Request Smuggling vulnerability or weakness.
Products Associated with CVE-2026-15634
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Affected Versions
IBM WebSphere Application Server:- Version 9.0 is affected.
- Version 8.5 is affected.