CVE-2026-15396

IBM WebSphere Application Server IBM WebSphere Application Server - Liberty HTTP Request Smuggling

Published Sep 14, 2026 CVSS 3.1 · 6.5 Medium EPSS < 1% KEV · Not listed
Description
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.

Remediation

Vendor Solution

IBM strongly recommends addressing the vulnerabilities now by applying the fix pack(s) listed below. For IBM WebSphere Application Server traditional: For V9.0.0.0 through 9.0.5.28: · Apply Fix Pack 9.0.5.29 SB0030823 (availability September 2026) or later fix pack.  For V8.5.0.0 through 8.5.5.30: · Apply Fix Pack 8.5.5.31 https://www.ibm.com/support/pages/node/7285869 (availability September 2026) or later fix pack.  For IBM WebSphere Application Server Liberty 17.0.0.3 - 26.0.0.8: · Apply Liberty Fix Pack 26.0.0.9 https://www.ibm.com/support/pages/node/7285875 (availability September 2026) or later fix pack.

Tracking

Sign in to view the affected projects.

Advisories

No advisories available
History
Type Values Removed Values Added
Description 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. 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.
Title IBM WebSphere Application Server prior to 9.0.5.29 and 8.5.5.31 are affected by multiple vulnerabilities IBM WebSphere Application Server IBM WebSphere Application Server - Liberty HTTP Request Smuggling
First Time appeared Ibm websphere Application Server Liberty
CPEs cpe:2.3:a:ibm:websphere_application_server_liberty:17.0.0.3:*:*:*:*:*:*:*
cpe:2.3:a:ibm:websphere_application_server_liberty:26.0.0.8:*:*:*:*:*:*:*
Vendors & Products Ibm websphere Application Server Liberty
References
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description 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.
Title IBM WebSphere Application Server prior to 9.0.5.29 and 8.5.5.31 are affected by multiple vulnerabilities
First Time appeared Ibm
Ibm websphere Application Server
Weaknesses CWE-444
CPEs cpe:2.3:a:ibm:websphere_application_server:8.5.0:*:*:*:*:*:*:*
cpe:2.3:a:ibm:websphere_application_server:8.5:*:*:*:*:*:*:*
cpe:2.3:a:ibm:websphere_application_server:9.0.0:*:*:*:*:*:*:*
cpe:2.3:a:ibm:websphere_application_server:9.0:*:*:*:*:*:*:*
Vendors & Products Ibm
Ibm websphere Application Server
References
Metrics cvssV3_1

{'score': 6.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
ibm
Published
Updated
Oct 22, 2026, 6:55 PM
Reserved
Jul 10, 2026, 1:16 PM
Status
Awaiting Analysis
Published
Sep 14, 2026, 8:16 PM
Modified
Oct 22, 2026, 7:17 PM