WavPack 5.5.0 contains a fix for CVE-2021-44269 wherein encoding a specially crafted DSD file causes an out-of-bounds read exception.
The other major change was the addition of the --drop option and the ability to add brace-delimited default option parameters to the executable filename. On Windows, these improvements make using the WavPack executable icons as "drag and drop" targets much easier and more flexible. For details on using this feature see the user manual
For the remaining minor fixes and improvements, see the official NEWS file.
Note that I am no longer able to generate binaries for macOS. These should probably be obtained from HomeBrew anyway, once that's been updated to 5.5.0.