Xftp FTP Client version up to and including 3.0 (build 0238) contain a stack-based buffer overflow vulnerability triggered by a maliciously crafted PWD response from an FTP server. When the client connects to a server and receives an overly long directory string in response to the PWD command, the client fails to properly validate the length of the input before copying it into a fixed-size buffer. This results in memory corruption and allows remote attackers to execute arbitrary code on the client system.
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).