An Avalanche tranche vault associated with Fence Finance and Valinor Digital was drained of approximately $1.01 million in USDC, according to an October 28 security alert from blockchain protection company Blockaid.
Blockaid said an attacker used a flash loan to mint inflated tranche shares and redeem the vault’s remaining stablecoins. The initial alert identified roughly two transactions involved in the exploit. Public transaction records on Avalanche offer a way to examine the reported transfers, although the operator’s full technical findings have not been published.
What happened to the Avalanche USDC vault?
The affected system used a tranche structure, in which different positions in a lending arrangement can have distinct rights and risk exposures. According to Blockaid, the attacker exploited the vault’s handling of those positions to withdraw USDC that should not have been available for redemption.
The reported loss of roughly $1.01 million is specific to this vault. There is no indication from the initial alert that the broader Avalanche network was compromised or that every application using USDC on Avalanche was affected.
Blockaid associated the vault with Fence Finance and Valinor Digital, but that does not establish which party administered or audited the affected contract. No definitive attribution of operational responsibility should be drawn from the alert alone.
Investigation and recovery remain open
The central outstanding questions include the precise contract-level root cause, the number of affected depositors, whether any assets have been recovered, and whether the vulnerable functionality has been disabled. Estimates and technical explanations may change when the operators publish a detailed account.
The case highlights how lending accounting can become a point of failure even when the underlying blockchain continues functioning normally. Projects using specialized settlement and tranche logic depend on secure implementations and clear risk controls.
BlockBriefing has separately covered a Solana wallet-drain incident associated with a third-party flaw.
Primary sources: Blockaid’s October 28 alert; Avalanche transaction record. This is an ongoing incident.
