Rating:

Overflow reference counter to cause UAF, which creates a relative read/write on the heap which can be upgraded to arbitrary read/write. Full solve script and writeup [here](https://github.com/welchbj/ctf/tree/master/writeups/2021/TetCTF/cache_v2).

Original writeup (https://github.com/welchbj/ctf/tree/master/writeups/2021/TetCTF/cache_v2).