Security Breach: Wanchain’s Cardano-BNB Bridge Exploited for $9 Million

A significant security breach has recently targeted Wanchain’s Cardano-BNB Bridge, a vital cross-chain protocol designed for asset transfers between the Cardano and BNB networks. The exploit led to the unauthorized drainage of approximately 515 million NIGHT tokens, valued at nearly $9 million, from the bridge’s treasury. While the incident highlights ongoing vulnerabilities within decentralized finance (DeFi) infrastructure, the underlying core blockchains remained unaffected.

The Mechanics of the Vulnerability

The compromise was traced back to a specific cryptographic flaw within the bridge’s TreasuryCheck validator, identified as "non-injective signed-message encoding." In a secure environment, every unique withdrawal request should generate a distinct encrypted message to ensure that a digital signature validates only one specific transaction. However, this vulnerability allowed multiple different withdrawal requests to produce identical encrypted messages. By exploiting this flaw, the attacker was able to reuse a legitimate signature from a previous transaction to authorize fraudulent withdrawals without needing access to the validator’s private keys.

Immediate Response and Industry Trends

Following the discovery of the theft, Wanchain moved quickly to halt the Cardano-BNB Bridge to prevent further losses and initiate a thorough investigation. The team confirmed that the impact was localized to the bridge itself, with no compromise to the core Cardano blockchain or the Midnight network. This incident occurs amidst a broader wave of DeFi exploits, including recent attacks on Allbridge Core and Ostium; however, data from DeFiLlama suggests a silver lining. Despite the frequency of these attacks, the total value lost in crypto exploits has reportedly decreased from $2.135 billion in mid-2025 to $1 billion by July 2026, indicating an overall improvement in ecosystem-wide security measures.