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Vulnerability · Published Sep 14, 2026 · Assigned by ibm

CVE-2026-15396IBM WebSphere Application Server IBM WebSphere Application Server - Liberty HTTP Request Smuggling

Medium 6.5

In plain English

A medium-severity security flaw in WebSphere Application Server from IBM. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 31% of all known vulnerabilities).

Severity (CVSS 3.1)6.5Medium
Exploit odds (30 days)0.4%top 69.3% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official 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.

Affected products (as reported)

VendorProductVersions
IBM WebSphere Application Server 9.08.5
IBM WebSphere Application Server - Liberty 17.0.0.3 – through 26.0.0.5

Weakness: CWE-444 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

References