Yesterday, I was analysing CPU patches for a 11.5.9 instance. That is when I found out that 11.5.9 is desupported as far as CPU patches are concerned since July 2008. Below is the extract from the July 2008 CPU advisory for EBS (Note 605117.1).
Oracle E-Business Suite Release 11.5.9 has been desupported as of 01-July-2008.
Hence, there would not be any further CPUs released by Oracle for 11.5.9. To verify this, I checked the Oct 2008 CPU advisory for EBS (note 738921.1), which expectedly did NOT contain any CPUs for 11.5.9.