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.

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
--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
--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
--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.

CVE-2026-8646

References