You can download this fixpack from here.
More information about how to install fixpacks for IBM Connections can be found here.
You will find a list of the fixes via this link.
If you are using IBM Connections Content Manager then you will need to update Filenet to 5.2.0 FixPack 1 (FP1) as well. More information here.
IBM Connections 4.5 Cumulative Refresh 1 (CR1) just arrived