I read about SHA3 and would like to study its weak point,
Are there any cryptographic attacks on SHA3-based HMAC?
There are many attacks on Keccak:
None of them are even close to actually breaking it in a practical way and they only apply to plain Keccak but the HMAC construction is known to be very resilient. Specifically HMAC-SHA1 and HMAC-MD5 seem to remain secure although neither MD5 nor SHA1 are.