Bug bounty platform Immunefi says white hat hacker Gerhard Wagner submitted a critical vulnerability affecting the Polygon Plasma Bridge on October 5, 2021 that allows attackers to withdraw their burn transactions from the bridge multiple times for up to 223 times. About $850 million is at risk, and an attack with just $100,000 would result in a loss of $22.3 million. Polygon confirmed the bug and immediately began fixing the underlying issue, which was resolved within a week. Polygon agreed to pay up to $2 million for the submission.