Recently, hackers has been developing fast propagat- ing worms exploiting vulnerabilities that had just been dis- closed by security experts. Those attacks particularly ex- pose servers: this class of applications is constantly con- nected to the Internet and must meet uptime constraints. Hence they often run unprotected until the next scheduled update. In this paper, we propose a just-in-time protection for servers based on runtime injection of pre-made patches. The runtime injection permits to deal with uptime con- straints and induces only a minimal overhead over the vul- nerable code and only when a vulnerability is known to ex- ist. The pre-made patches forbid exploitation of most com- mon vulnerabilities (45% of attacks reported by Debian se- curity in 2005 affecting C softwares) and allows continuous servicing.