There is a new Mapbox Style community module available, which adds support for an interoperable json styling language. For more details, refer to the documentation.
GSIP 158 – NetCDF output support for variable attributes and extra variables. This improvement adds the ability to set attributes on output NetCDF variables, copy attributes from source NetCDF/GRIB variables, and copy scalar variables from NetCDF/GRIB sources including ImageMosaics. See the documentation for details.
Allow disabling usage of SLD and SLD_BODY in WMS requests (also for virtual services).
Various improvements to virtual services, including lookup and GML 3 encoding handling
Namespace filtering on capabilities returns all layer groups (including the ones in other workspaces)
Not possible to PUT workspace using REST
GeoServer Home Page missing information messages
Style Editor Preview Legend Fails on non-SLD Styles
Integrated GWC does not work with layer and layer group specific services
Generating a raster SLD style from template produces a functionally invalid style