Osmosis has paused inflows and outflows of nBTC following a double-spend exploit on the Nomic chain that allowed an attacker to generate fake Bitcoin vouchers and send them to the protocol. The incident affected 39.84 nBTC, equivalent to approximately 36 percent of the backing for Osmosis's Alloyed BTC asset.
An emergency upgrade froze 22.65 BTC in the attacker's address. Osmosis and the Inter-Blockchain Communication protocol that connects Nomic to Osmosis remained uncompromised; the vulnerability existed solely within Nomic's implementation. The protocol is now seeking governance approval to seize the frozen assets and replenish Alloyed BTC's full backing using Bitcoin from Osmosis's community pool.
Nomic is a Bitcoin bridge protocol designed to allow Bitcoin holders to mint nBTC, a wrapped representation of Bitcoin on Cosmos chains. Alloyed BTC is an Osmosis-native asset that bundles multiple Bitcoin bridge implementations for redundancy. The 39.84 nBTC represents a material portion of one of those backing reserves.
Double-spend exploits occur when a blockchain's consensus mechanism fails to prevent the same unit of value from being spent twice. On Nomic, this failure allowed the attacker to generate counterfeit vouchers representing Bitcoin deposits that never occurred, inflating the nBTC supply beyond actual Bitcoin held in custody.
Osmosis has not yet announced a timeline for the governance vote on asset seizure and pool drawdown. If approved, the remediation would restore confidence in Alloyed BTC's one-to-one backing but would deplete a portion of community-controlled reserves allocated for protocol operations and incentives.
The exploit exposed the security risks in cross-chain bridge designs, where a single implementation failure can contaminate assets across multiple protocols. Osmosis's decision to halt trading in the affected asset prevented further damage but left holders unable to exit positions during the recovery process.
The timeline for resuming nBTC services depends on governance approval and the technical execution of the seizure and restoration plan. Osmosis governance must vote on whether to proceed with the community pool drawdown.
