PANews reported on May 20th that Threshold Network posted on its X platform that at 18:04 Beijing time on May 18th, an attacker attempted to mint tBTC without depositing the underlying BTC, but failed. No invalid tBTC was generated, and user funds were not at risk. Out of caution, given the increased frequency of malicious activity across the crypto ecosystem, Optimistic Minting has been temporarily suspended. Minting is now conducted via a sweeping mechanism, extending the minting time from approximately 1.5 hours to approximately 6-7 hours.

According to reports, tBTC's basic security model involves a decentralized network of signers holding the underlying Bitcoin and verifying each native minting through verifiable Bitcoin SPV proofs. Optimistic Minting employs a different trust model, with deposits confirmed by Minter and Guardian proofs instead of SPV proofs, and a minting time of approximately 1.5 hours.