Osmosis said the Nomic chain was attacked through a vulnerability in a custom forwarding mechanism, allowing an attacker to carry out a double-spending exploit that generated fake receipts and exchanged them for nBTC on Osmosis.

According to Osmosis, the exploit was centered on Nomic’s custom forwarding mechanism rather than Osmosis or IBC. The attacker used the flaw to create fake receipts and redeem them for nBTC on Osmosis, in what the project described as a double-spending attack.

Osmosis said 39.84 nBTC had been minted through the exploit path. It added that roughly 36% of the asset’s collateral was stored in Alloyed BTC synthetic assets, linking the incident directly to the collateral backing of that product.

In response, the Osmosis governance sub-DAO froze deposits and withdrawals between Nomic and Alloyed BTC. Osmosis also said it completed an emergency upgrade with validators that froze 22.65 BTC in the attacker’s address.

The remaining recovery steps are still pending. Osmosis said it will submit a governance proposal to confiscate the frozen assets and request permission to use the remaining BTC in the community fund to cover the shortfall and restore full collateral for Alloyed BTC.

Why It Matters

The incident highlights a recurring risk in cross-chain asset design: a failure in a connected mechanism can affect wrapped or synthetic BTC products even when the destination chain and the core interoperability layer are reported to be intact. For users and protocols in the Cosmos ecosystem, that makes implementation details around forwarding, minting, and redemption at least as important as the security of the base messaging standard.

It also puts governance-led recovery mechanisms under scrutiny. Freezing attacker-held funds, coordinating an emergency validator upgrade, and potentially using community assets to backstop collateral show how decentralized systems may respond after an exploit, but they also raise practical questions about loss allocation, asset recovery, and trust in synthetic collateral structures.