Within Ultimaker we do not use Java for our internet connected customer facing products, this includes but is not limited to
- Firmware of the Ultimaker 3, Ultimaker S3, Ultimaker S5, Ultimaker 2+ Connect, or other Ultimaker printers
- Cura slicer
- Digital Factory
- Contributor portal
- Account services
So in no way you are vulnerable to issues surrounding Log4J by using Ultimaker products.