BitBTC's Optimism bridge is trivially vulnerable. Their team has ignored my messages, so I'm going to publish the critical exploit here. https://twitter.com/optimismFND/status/1469083380461408257β¦
Sigh, just to be clear here, this is a bug in BitBTC's code and NOT a bug in Optimism's code. BitBTC has a custom bridge and doesn't use the standard bridge that Optimism provides. Probably worth clarifying this in the main thread.