IBM WebSphere Application Server 9.0, and 8.5 and IBM WebSphere Application Server - Liberty 17.0.0.3 through 26.0.0.6 are vulnerable to a denial of service, caused by sending a specially-crafted request. A remote attacker could exploit this vulnerability to cause the server to consume memory resources.
IBM strongly recommends addressing the vulnerability now by applying a currently available interim fix or fix pack that contains the fix for APAR PH71631 and PH71370. To determine if a feature is enabled for WebSphere Application Server Liberty, refer to How to determine if Liberty is using a specific feature https://www.ibm.com/support/pages/node/6553910 .
For IBM WebSphere Application Server Liberty 17.0.0.3 - 26.0.0.6 using the servlet-3.0, servlet-3.1, servlet-4.0, servlet-5.0, servlet-6.0, servlet-6.1, websocket-1.0, websocket-1.1, websocket-2.0, websocket-2.1, or websocket-2.2 feature:
· Upgrade to minimal fix pack levels as required by the interim fix and then apply the Interim Fix that resolves PH71631 https://www.ibm.com/support/pages/node/7276381
--OR--
· Apply Fix Pack 26.0.0.7 or later (targeted availability 3Q2026).
For IBM WebSphere Application Server traditional:
For V9.0.0.0 through 9.0.5.28:
· Upgrade to minimal fix pack levels as required by the interim fix and then apply the Interim Fix that resolves PH71370 https://www.ibm.com/support/pages/node/7276399
--OR--
· Apply Fix Pack 9.0.5.29 or later (targeted availability 3Q2026).
For V8.5.0.0 through 8.5.5.29:
· Upgrade to minimal fix pack levels as required by interim fix and then apply Interim Fix that resolves PH71370 https://www.ibm.com/support/pages/node/7276399
--OR--
· Apply Fix Pack 8.5.5.30 or later (targeted availability 3Q2026).
Additional interim fixes may be available and linked off the interim fix download page.