Bitcoin security researcher and Bitcoin developer Antoine Riard quits development of the Lightning Network due to security concerns and fundamental challenges facing the Bitcoin ecosystem. It believes that the new alternative loop attack puts the Lightning Network in a "dangerous position." An attacker with a substitution loop attack can exploit inconsistencies between various mempools to steal funds from payment channel participants. Riard noted that addressing new types of attacks may require changes to the underlying Bitcoin network. (Cointelegraph)