ArcGIS Notebook Server 11.0 does not include Log4j.
For customers using ArcGIS Notebook Server 10.9.1, 10.9, 10.8.1, and 10.7.1, upgrade to the latest release (11.0+) or install the ArcGIS Notebook Server Security Patch.
- 10.9.1: https://support.esri.com/en/download/8004
- 10.9: https://support.esri.com/en/download/8008
- 10.8.1: https://support.esri.com/en/download/8009
- 10.7.1: https://support.esri.com/en/download/8010