In this paper we examine the current state of play with regards to the security of smart city initiatives. Smart city technologies are promoted as an effective way to counter and manage uncertainty and urban risks through the effective and efficient delivery of services, yet paradoxically they create new vulnerabilities and threats, including making city infrastructure and services insecure, brittle, and open to extended forms of criminal activity. This paradox has largely been ignored or underestimated by commercial and governmental interests or tackled through a technically-mediated mitigation approach. We identify five forms of vulnerabilities with respect to smart city technologies, detail the present extent of cyberattacks on networked infrastructure and services, and present a number of illustrative examples. We then adopt a normative approach to explore existing mitigation strategies, suggesting a wider set of systemic interventions (including security-by-design, remedial security patching and replacement, formation of core security and computer emergency response teams, a change in procurement procedures, and continuing professional development). We discuss how this approach might be enacted and enforced through market-led and regulation/management measures, and then examine a more radical preventative approach to security.