Can a Contract’s Fallback Function Intentionally Consume More than 2,300 Gas?

Yes, a contract's fallback function can be programmed to intentionally consume more than 2,300 gas by including gas-intensive operations, such as writing to storage or executing a loop. If such a contract receives Ether via transfer or send , the transaction will revert due to an out-of-gas error in the fallback function.

This is a potential denial-of-service vector for legitimate transfers.