Cryptocurrency custody technology provider Fireblocks has discovered a critical vulnerability in cryptocurrency custody company BitGo’s Threshold Signature Scheme (TSS) wallet, putting users’ private keys at risk of being hacked, The Block reported. According to Fireblocks researchers, the vulnerability is due to the lack of mandatory zero-knowledge proof implementation in the TSS wallet protocol. This omission has the potential to make it possible for attackers to extract users' private keys and obtain their assets. After BitGo learned of the vulnerability in December 2022, it quickly suspended the affected wallet service, then released a patch in February 2023 to solve the problem, and notified users to update the system before March 17. Fireblocks did not say whether any user assets were lost as a result of the bug. Idan Ofrat, Fireblocks co-founder and chief technology officer, said, "The vulnerability is due to the wallet provider not following a well-vetted encryption standard." Fireblocks said it worked closely with BitGo to address the vulnerability and improve the security of its wallet service.