Analysis of the $70 Million UPCX Hack: The Critical Threat of Compromised Private Keys

In April 2025, the open-source crypto platform UPCX suffered a $70 million security breach, not from a smart contract flaw, but from a compromised private key that allowed an attacker to execute a malicious contract upgrade.1 This incident highlights the critical need for robust off-chain security measures, such as multi-signature wallets and cold storage for privileged keys, as relying solely on smart contract audits is insufficient to protect against these types of attacks.2