Vulnerability in IBM Websphere Application Server
CVE-2026-15396
IBM WebSphere Application Server 8.5 and 9.0, and IBM WebSphere Application Server - Liberty 17.0.0.3 through 26.0.0.8 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 class: HTTP Request Smuggling
Published · last modified .
CVSS v3 metric
CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N.
EPSS exploit prediction
EPSS: 0.004 (30.5th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 30th percentile — 30.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.004 · change: +0.001
Affected products
- IBM Websphere Application Server — versions 8.5, 9.0
- IBM Websphere Application Server - Liberty
Weakness classification (CWE)
References
- www.ibm.com/support/pages/node/7286610 (vendor-advisory, patch)
- www.ibm.com/support/pages/node/7286611 (vendor-advisory, patch)
Frequently asked questions
- What is CVE-2026-15396?
- CVE-2026-15396 is a medium-severity vulnerability in IBM Websphere Application Server, classified under Inconsistent Interpretation of HTTP Requests (HTTP Request/Response Smuggling). CVSS score: 6.5/10. Published 2026-09-14.
- How severe is CVE-2026-15396?
- Medium severity. CVSS v3 base score is 6.5 out of 10.