I don't know man, the MIT Digital Currency Initiative found a pretty bad one last August:
https://medium.com/@neha/cryptographic-vulnerabilities-in-io...
> the IOTA developers had written their own hash function, Curl, and it produced collisions (when different inputs hash to the same output). Once we developed our attack, we could find collisions using commodity hardware within just a few minutes, and forge signatures on IOTA payments. We informed the IOTA developers, they patched their system, and we wrote a vulnerability report