Disinformation draws unprecedented public attention. Current digitalization and technological transformation alter how people consume information, perceive the world, and make decisions. A diverse set of actors, ranging from foreign governments to terrorist outlets and fraudsters, use cyber-mediated information operations for a variety of purposes, including gaining political or economic influence. Disinformation and social manipulation through cyber-mediated channels alter basic social mechanisms and threaten foundational democratic structures. Political polarization, radicalization, and violent extremism are now partly connected to informational dynamics across the cyber-space. Authoritarian governments combine new technologies and the features of the new information environment to suppress political opposition, freedom of expression or certain racial or ethnic groups. In light of the recent trends and growing knowledge across the scientific and policy research literature, this paper presents an overview of the emerging cyber-mediated security threats as well as their underlying social and cognitive dynamics. The first section delivers an assessment of how the modern information environment and social-political dynamics change vis-à-vis the threat of malign influence across the cyber-space. The second section offers some selected insights from the events and activities on social
media platforms, with a specific focus on the factors that reach beyond the basic concept of fake-news. Finally, the third section explores a tiny fraction of the scientific literature to illustrate both social and cognitive features that relate to current and future challenges.