Base Vault Loses $6M in wstETH: Aave Intact, the Multisig Failed
On October 4 an unidentified vault on Base lost 1,783 wstETH, about $6 million. An attacker contract got onto the whitelist, borrowed Aave tokens against the vault's position and moved them out. According to ExVul, a minute before the attack the Safe multisig signed that access twice with the owners' genuine keys. Here is the timeline and what it means for anyone holding ETH in DeFi on L2.
What happened
On October 4, 2026, an unidentified vault on the Base network lost 1,783 wstETH, worth about $6 million. wstETH is Lido's wrapped staked ether: the same ETH, earning staking yield. The vault held a large position in Aave V3 and was controlled by a 3-of-7 Safe multisig. Who is behind the seven signers is still unknown: no project has claimed the vault.
The attack itself was simple. A new contract was added to the vault's whitelist, which gave it the right to draw funds. It borrowed aBaswstETH, Aave's interest-bearing token on Base that represents a wstETH deposit, forwarded the tokens to the attacker's address, and there they were redeemed through Aave for plain wstETH. ExVul counted 1,783.067 aBaswstETH leaving in six transfers.
The Base network and Aave's contracts were not hit. Access control failed: someone with owner rights let an outside contract reach the money. It is a good moment to check where your ether sits: on an exchange, in someone else's strategy, or in a wallet only you hold the keys to. You can pull part of your coins out of complex strategies without an exchange account: a crypto exchange with no registration sends the swapped coins straight to your address.
October 4 timeline
Times are UTC, based on ExVul's breakdown and posts by security firms on X.
| Time | Event |
|---|---|
| 08:52 | The owner's Safe removes the attacker contract from the whitelist |
| 08:53 | The same Safe re-enables it |
| ~08:54 | First aBaswstETH borrow, about 70 seconds later |
| 09:20 | Blockaid flags the attack, first estimate $2.02 million |
| 09:56 | PeckShield: 1,783 wstETH drained, about $6 million |
| 09:59 | CertiK describes a proxy contract that borrowed ~1,783 aBaswstETH |
| 10:09 | ExVul: 1,783.067 aBaswstETH in six outflows |
Blockaid started at $2 million and raised its estimate past $6 million as the attack went on. In the end every firm's numbers agreed on 1,783 wstETH. According to TokenPost, about $31.7 million was still in the vault when the first reports came out, and it was at risk too.
Keys, not an Aave bug
ExVul's key finding is two transactions a minute before the attack. At 08:52 the multisig removed the attacker contract from the whitelist, and at 08:53 it put it back. In both transactions three Safe owner signatures check out as genuine. For a 3-of-7 setup that is exactly the quorum.
So the attacker did not need to break any code: they had three valid signatures. There are two options. Either three signers' keys were stolen, or some of them signed something other than what they thought. That is how blind signing works: the wallet shows an unreadable blob of data and a person clicks "Confirm". TokenPost adds a detail: the owners had not sent a single transaction from this Safe for 25 days before the attack. Social engineering and collusion are being discussed, but neither has been proven.
There is no public response yet. Nobody has published a post-mortem, frozen funds or offered a bounty. Aave had made no statement at the time of writing either: the protocol was only the venue where the tokens were redeemed. Unverified community tracking shows part of the loot starting to move to Ethereum through Lido infrastructure, and the attacker's address no longer holds any notable wstETH.
A week of attacks on DeFi add-ons
The vault hack was not the only case this week where an add-on was hit rather than the protocol itself.
- On October 1 an attacker hit FlashLoopAdapter, an Aave v3 Loop module for Safe that builds leveraged lending loops. According to SlowMist, 114.09 ETH, about $307,000, left two multisigs. The attacker plugged in a fake Safe and fooled the module's access check, while Aave's pools worked as designed.
- On October 3 GoldPesa's GPXHooks contract on Base was drained of about $115,000 in USDC. It is a Uniswap v4 hook, and the attack needed no admin rights at all.
Early recaps lumped these cases together as a series of attacks on Aave, but only FlashLoopAdapter involves Aave, and the protocol was not breached there either. What all three share is a weak spot between the user and a proven protocol: an adapter, a module, a hook, a whitelist, a multisig. For scale, it helps to recall how much crypto hacks cost projects in September 2026.
What it means for ETH and wstETH holders on L2
Aave, Lido and Base have run for years and passed many audits. But yield in L2 vaults and strategies usually comes through an add-on: someone else's contract manages your deposit, and it has admin keys, a whitelist and an upgradeable proxy. The vault in this story was exactly that, with an upgradeable proxy and positions in Aave V3. Such a setup is only as reliable as its weakest part.
When you put wstETH into a strategy, you trust not only Aave but also whoever holds the strategy's keys. Their names are often unknown, as in this case. It is essentially the same choice as between an exchange and your own wallet, and our article on how a non-custodial wallet differs from an exchange account covers the difference in detail. If you also want less exposure to a single asset, you can exchange ETH to bitcoin for part of your ether and keep it on another network.
What to do now
- List where your ether sits: vaults, loops, pools. For each one, decide what share you are ready to lose.
- Check what you sign. If your wallet shows unreadable data instead of a clear action, do not confirm. In a multisig, verify the transaction hash on a second device.
- Revoke approvals you no longer need. Old token approvals and enabled Safe modules stay active for years, and both Etherscan and Basescan have an approval checker.
- Do not keep everything in one strategy. Split funds between your own wallet and one or two protocols, without leverage where you do not need it.
- Protect your keys. Self-custody is only as safe as your seed phrase storage: see our separate guide on how to store a seed phrase so you never lose access to your coins.
Some coins in your own wallet
Moving ether out of a strategy and holding it yourself is the simplest step after news like this. If you also want to spread the risk, VertEXchange swaps coins with no account, email or phone number: you enter your address, send your coins and receive the swapped coins directly to it, with no balance in between. You can choose a floating or a fixed rate, and a fixed rate holds for about 15 minutes.
For example, you can swap ETH for USDT on TRC20 for part of your holdings and wait in stablecoins until you decide where to put them. When you want to go back to ether, it is just as easy to buy ETH with USDT TRC20 and receive it straight in your own wallet.
FAQ
Was Aave hacked?
No. According to PeckShield, CertiK and ExVul, Aave's contracts worked as designed. The attacker got access through the vault's whitelist, and the owners' multisig approved it with transactions carrying genuine signatures.
Whose vault is it?
Unknown. It is controlled by a 3-of-7 Safe with unidentified signers, and no project has claimed it.
Should I pull my wstETH out of DeFi on L2?
That is your call. It makes sense to know who holds the admin keys of every strategy you use and not to keep more in any one of them than you are ready to lose. Keeping part of your funds in your own wallet removes the dependence on other people's keys.
Swap ETH with no account and receive the coins straight to your own address.
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