Optimism quietly patches critical testnet flaws after rival's tip-off

The Layer 2 network Optimism OP -4.31% has repaired two critical vulnerabilities on its testnet at least several weeks after learning of them. 

Offchain Labs, which first identified the vulnerabilities, stated on Friday that Optimism updated its testnet on April 25. The since-fixed security flaws allowed bad actors to manipulate the chain's history and execute other “subtle attacks,” the software firm said.

On March 22, Offchain Labs alerted Optimism about two issues with its testnet: Bad actors could force the OP Stack fraud-proof mechanism to accept a fraudulent chain history, and an exploiter could prevent it from accepting a correct chain history.

“These are difficult problems to solve,” Offchain Labs, which is a competitor of Optimism, said in the statement. It added that fraud-proof protocols and their timing aspects are “very difficult” to design.

According to Offchain Labs, Optimism has since modified its timer-handling code to fix the vulnerabilities. To be sure, Layer 2 testnets, or test networks, exist to identify networks’ security flaws before their official launches.