The aim of this annual report is to present an updated assessment of the threat posed by non-state actors' use of chemical, biological, radiological, or nuclear (CBRN) materials to cause adverse effects on society. The content is based solely on open-source information and includes a selection of incidents that occurred in 2020. The report has been produced by a research group at FOI (Swedish Defence Research Agency), within the framework of a grant from the Swedish Ministry of Defence. No known CBRN-related terrorist attack has occurred during 2020. However, there is still a widespread concern for the occurrence of this type of attack and the consequences it may generate in the society. Propaganda and threats related to CBRN attacks and instructions for carrying them out are still being disseminated within violent extremist communities, with the purpose of spreading fear and inspiring sympathisers to take action. Propaganda and expressions of threat during this year have largely been influenced by the ongoing COVID-19 pandemic and its effects and consequences.