Simple Web Server 2.2 rc2 contains a stack-based buffer overflow vulnerability in its handling of the Connection HTTP header. When a remote attacker sends an overly long string in this header, the server uses vsprintf() without proper bounds checking, leading to a buffer overflow on the stack. This flaw allows remote attackers to execute arbitrary code with the privileges of the web server process. The vulnerability is triggered before authentication.
A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function).