MJM Core Player (likely now referred to as MJM Player) 2011 is vulnerable to a stack-based buffer overflow when parsing specially crafted .s3m music files. The vulnerability arises from improper bounds checking in the file parser, allowing an attacker to overwrite memory on the stack and execute arbitrary code. Exploitation is triggered when a user opens a malicious .s3m file, and the exploit bypasses DEP and ASLR protections using a ROP chain.
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).