Linux Heap Exploitation Intro Series: Set you free() – part 2

This blog post documents exploit-development for a heap-based buffer overflow in the apngopt PNG optimizer. It explains how crafted APNG chunk sizes and heap massaging can produce controlled fastbins/unsorted-bin metadata corruption, demonstrates a proof-of-concept file and debugging techniques (gdb/villoc), and discusses limitations (ASLR, allocator checks) that prevented full instruction-pointer control.