Wanchain Bridge Exploit Drains $9 Million in NIGHT Tokens

BlockSec’s investigation points to a flaw in the TreasuryCheck validator, which reportedly fails to properly separate data fields when creating messages for signing. This lack of structure may have allowed an attacker to reorganize field values while maintaining an identical byte string, effectively enabling a signature reuse attack. The security firm noted that the bridge failed to utilize Cardano’s existing SerialiseData function, which would have enforced clear boundaries between data sets and prevented the ambiguity exploited during the incident.

While the market impact was swift—erasing roughly $9 million in value—the Midnight Foundation emphasized that the vulnerability is contained within Wanchain’s third-party infrastructure. The foundation confirmed that the Midnight blockchain, its consensus system, and core network validators remain unaffected. Wanchain, which launched cross-chain support for the token in December 2025, has yet to publish a full technical postmortem. The incident underscores persistent security risks inherent in cross-chain bridges, which frequently serve as high-value targets due to the complex verification systems required to move assets between distinct networks.