The THREDDS development team released version 4.6.20 of the TDS on February 16th, 2022. This release contains various upgrades to third party libraries that address security exploits, as well as a bug fix in the WMS service. You can find the full release notes here.
Note: The TDS downloads page has moved! You can now find TDS jar files at https://downloads.unidata.ucar.edu/tds/
For TDS 5.x users - the 5.4 release will be ready soon, but we are still working to address a number of reported bugs prior to the release date, which remains TBA. In the meantime, please continue to the SNAPSHOT release available on the TDS downloads page.