Self-propagating worms have been terrorizing the Internet for several years and they are becoming imminent threats to large-scale Peer-to-Peer (P2P) systems featuring rich host connectivity and popular data services. In this paper, we consider topological worms, which exploit P2P host vulnerabilities and topology information to spread in an ultra-fast way. We study the feasibility of leveraging the existing P2P overlay structure for distributing automated security patches to vulnerable machines. Two approaches are examined: a partition-based approach, which utilizes immunized hosts to proactively stop worm spread in the overlay graph, and a Connected Dominating Set(CDS)-based approach, which utilizes a group of dominating nodes in the overlay to achieve fast patch dissemination in a race with the worm. We demonstrate through analysis and simulations that both methods can result in effective worm containment.