Base vault drain: $6M in wstETH, gas from Tornado Cash — and 1,000 wstETH stuck in a seven-day bridge window

The vault, 0xD1895f2019c2152FC2b9022D57f19198c4CFCABC, held a leveraged wstETH position on Aave. It is run by a Safe, 0x6b27512a5943Ed327f6cb6C3EC1f0398229f42C4, that needs three of seven signatures; nobody has said whose they are. The vault lets whitelisted contracts move its Aave receipt tokens.

At 08:52 and 08:53 UTC the Safe sent two transactions to the vault that changed that whitelist — according to ExVul, first removing and then re-adding the attacker’s contract, 0xcdFE91301356da873562EF513828a60dba1F569d. We checked both: each carries three valid owner signatures. In other words, the change went through the vault’s own approval process. Whether three owners’ keys were stolen or something else happened, the chain does not say.

Two minutes later the contract began pulling the vault’s aBaswstETH — a 1-token test at 08:55, then 100, 500, 500, 500 and 182.067 between 09:08 and 09:12. Each batch was passed straight to the wallet that deployed the contract, 0x0B5126e1bc27C0de77e02e97945760A674EdB034, which at 09:23 redeemed all 1,783.067 aBaswstETH on Aave for wstETH in one transaction.

The attacker wallet on Base was empty until 06:49 UTC, when 0.05 ETH arrived through Base’s own bridge from Ethereum. The sender on Ethereum, 0x707877cE44282896E417EbBDc5e7d4620A3366EF, had been created minutes earlier: at 06:43 it received 0.098 ETH withdrawn from Tornado Cash’s 0.1 ETH pool, and at 06:46 it bridged 0.05 ETH of it to the attacker wallet on Base.

So the attack was prepared at least two and a half hours before the first token moved, and its fuel was laundered first. That rules out an accident or a signer acting on impulse: someone set this up.

At 10:47 the attacker wallet sent 1,782.067 wstETH to a new address, 0xC73448432a05deeA5Ea18a07D3b5d9ccf6297f8D (after a 1 wstETH test an hour earlier). That address chose the slowest exit available: Lido’s official wstETH bridge from Base to Ethereum. It withdrew 1 wstETH at 09:27 and 1,000 wstETH at 12:10, both to its own address on Ethereum, and it paid for Ethereum gas through Gas.zip.

A withdrawal from Base to Ethereum is not instant. It has to be proved on Ethereum and then wait out a challenge period of about seven days before the coins can be claimed. The attacker proved both withdrawals on Ethereum, at 10:43 and 13:44 UTC on 4 October. Until about 11 October, those 1,001 wstETH exist on neither chain in spendable form. When the window closes they will appear at the same address on Ethereum.

The remaining 782.067 wstETH is still on Base at 0xC73448432a05deeA5Ea18a07D3b5d9ccf6297f8D, as of 4 October 16:00 UTC — most likely waiting for the same route.

wstETH cannot be frozen by its issuer. What the seven days do give is time: for the vault’s owners to come forward, for Base and its security council to look at the withdrawals, and for every exchange to recognise the address before the coins arrive.

It does not say who controls any address, and it does not say any signer of the Safe is responsible. That the whitelist change carried three valid signatures is a fact on chain; how those signatures came to be made is not. The incident itself was first reported by Blockaid, PeckShield, CertiK and ExVul; the gas source, the bridge withdrawals and the balances are our own reading on 4 October 2026.