Recently, hackers has been developing fast propagating worms exploiting vulnerabilities that had just been disclosed by security experts. Those attacks particularly expose servers: this class of applications is constantly connected 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 constraints and induces only a minimal overhead over the vulnerable code and only when a vulnerability is known to exist. The pre-made patches forbid exploitation of most common vulnerabilities (45% of attacks reported by Debian security in 2005 affecting C softwares) and allows continuous servicing.