Security researchers have disclosed that an unidentified vault contract on Base, an Ethereum layer-2 network incubated by Coinbase, lost approximately $6 million after attackers exploited weaknesses in its whitelist and multisignature controls. The incident came to light on October 4, when blockchain security firm Blockaid identified unusual withdrawals from the contract. Within roughly 40 minutes, the estimated loss climbed from $2.02 million to about $6 million.

According to GoPlus, PeckShield, CertiK, and Exvul, the attacker borrowed 1,783.067 aBaswstETH from the vault and redeemed the Aave receipt tokens for approximately 1,783 wstETH. aBaswstETH represents wrapped staked Ether supplied to Aave's Base market, with wstETH — the wrapped form of Lido's staked Ether — as the underlying asset.

GoPlus Security Alert: On Base, a vault contract that no project team has publicly claimed was hit. 1,783.067 aBaswstETH was taken out, then redeemed on Aave V3 for about 1,783 wstETH. Loss is roughly $6 million. The vault holds a position on Aave V3 Base, sized in the tens… pic.twitter.com/v5yrcIIp5w
— GoPlus Security (@GoPlusSecurity) October 4, 2026

#PeckShieldAlert It appears that 0x0B5126…B034 has drained 1,783 $wstETH (~$6M) on #Base pic.twitter.com/zCd2VDst8t
— PeckShieldAlert (@PeckShieldAlert) October 4, 2026

The theft was not caused by a vulnerability in Aave's core lending contracts or in the Base network itself. Instead, investigators linked it to a failure involving the vault's multisignature governance and access controls. A newly created contract was added to the vault's borrowing allowlist through a Safe multisignature transaction. Allowlist controls like this one are designed to restrict which contracts can move a vault's position, so the exploit effectively turned a protective mechanism into the attack path. Once whitelisted, the contract could borrow the vault's Aave position and redeem the underlying assets.

The vault's operating owner is a three-of-seven Safe created through Safe Proxy Factory 1.4.1, a configuration in which any three of the seven signer addresses must approve a transaction before it executes. Safe is a multisignature wallet framework widely used across decentralized finance, making the operational security of signer keys a shared dependency for many protocols and treasuries. Seven signer addresses control the account, but their identities have not been publicly established. Investigators can trace the on-chain transactions, but blockchain records alone cannot determine whether the whitelist update resulted from stolen credentials, social engineering, an insider threat, or another governance failure.

Notably, the Safe had not executed a transaction on the vault for 25 days before two transactions were completed during the attack. This activity may indicate that the signers were manipulated or that an internal party approved the change. No security firm has publicly confirmed which explanation is correct.

Unclaimed Ownership and Remaining Exposure

The lack of a known owner has complicated the response. No project team has publicly acknowledged the vault, announced a remediation plan, or explained how the unauthorized whitelist addition was approved. That absence also leaves the usual recovery route of negotiating a bounty with an identified team without a counterparty. The vault is an OpenZeppelin transparent proxy — a proxy pattern in which the vault address delegates calls to a separate implementation contract — with a separate upgrade authority, adding another contract layer between the asset holder and the ultimate controller.

Approximately $31.7 million in assets reportedly remained in the vault after the withdrawal. An unidentified on-chain user later sent the attacker a message encouraging them to withdraw the remaining funds and requesting a tip, but there has been no publicly verified response.

For now, the direct systemic risk appears limited because Aave's Base deployment and the underlying blockchain remained unaffected. Nevertheless, the episode illustrates how privileged administrative functions can create a greater risk than the smart contracts they govern. Multisignature approval alone does not guarantee security when signer identities, transaction review procedures, and internal controls are weak.

The incident also places attention on wstETH liquidity. Selling approximately 1,783 wstETH could create short-term market pressure, although the receipt token's broader peg has not been shown to be at risk. Further details may emerge if the Safe signers, the vault's controlling organization, or the attacker publicly identify themselves. In the meantime, whether the remaining approximately $31.7 million stays untouched can be tracked directly on-chain.

Source: Metaverse Post