Base Vault Exploit Drains $6M in wstETH Via Whitelist

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So far no team has claimed the vault or issued a post-mortem. Because the signers stay unidentified, the cause remains contested, even though the stolen amount is clear.

How the Base Vault Exploit Unfolded

The drained contract is a vault proxy at 0xD1895f2019c2152FC2b9022D57f19198c4CFCABC on Base. It is an OpenZeppelin TransparentUpgradeableProxy, and a 3-of-7 Safe controls it.

Notably, that Safe is not new. It was created about 324 days before the drain, through Safe Proxy Factory 1.4.1. So this was an established setup, not a throwaway wallet spun up for the attack.

Around 08:55 UTC, a freshly whitelisted contract started borrowing aBaswstETH from the vault. Then it forwarded those aTokens straight to the attacker.

After a test transfer of 1 token, the outflows scaled fast. Six transfers totaling 1,783.067 aBaswstETH moved out in about 25 minutes, in chunks of 1, 100, 500, 500, 500, and 182.067.

Next the attacker redeemed the aTokens through Aave for roughly 1,783 wstETH. As a result, the vault was left with about 0.0007 wstETH at address 0x0B5126e1bc27C0de77e02e97945760A674EdB034.

The Whitelist Flip That Opened the Door

The key move came minutes earlier. At about 08:52 UTC, the Safe removed a newly deployed contract from the vault whitelist. Then it re-enabled the same contract at about 08:53 UTC.

According to PublicAML, both transactions carried three valid owner signatures from the same signing identities. So the on-chain permissions looked entirely normal.

Roughly 70 seconds after that re-approval, the borrowing began. Because the contract now sat on the allow-list, the vault treated it like a trusted strategy.

aBaswstETH is Aave V3’s interest-bearing receipt token for wstETH supplied on Base. wstETH itself is Lido’s wrapped staked ETH. Once whitelisted, the attacker contract could pull those aTokens and cash them out.

Why Base and Aave Were Not Compromised

This was an application-layer failure, not a chain-level one. In short, the vault’s own permissioning broke, while Base and Aave core contracts kept working as designed.

Aave simply honored a valid redemption of aTokens that the caller held. According to CertiKAlert, a newly deployed proxy borrowed about 1,783 aBaswstETH, then redeemed it through Aave for wstETH.

The scale stayed small against the wider network. Base DeFi TVL sat near $6.4 billion that day, so the drain was under 0.1% of chain value, according to DefiLlama.

Despite that, some posts loosely blamed “Coinbase Base” or Aave. Primary alerts reject that framing, since both systems functioned correctly throughout.

Was It a Hack, or an Owner Move?

Here the story splits. Security firms Blockaid, PeckShield, CertiK, and ExVul all frame the event as a Base vault exploit through unauthorized or compromised whitelist access.

PeckShieldAlert reported the 1,783 wstETH figure at 09:56 UTC. Minutes later, Blockaid updated its own estimate past $6 million and said the drain was still ongoing.

Blockaid’s first alert, at 09:20 UTC, had pegged the loss near $2.02 million across about four transactions. So the lower number was only a mid-attack snapshot, not the final tally.

The math lines up with market pricing too. wstETH traded near $3,360 that day, up about 0.69%. At that level, 1,783 tokens work out to roughly $6.0 million, matching the reported loss.

Yet not everyone agrees it was a hack. @deepcryptodive, Head of Risk Curation at KPK, argued it “doesn’t look like an exploit.” He noted the amount matched a June 5 deposit plus interest, moved by the team’s usual address.

He also pointed out that roughly 8,000 WETH stayed untouched in the vault. On that basis, he put “95% chance this is legit, and no hack.” PublicAML still tracks the flow as a drain, even while confirming the signatures were valid.

Where the Stolen wstETH Went

The attacker did not move everything at once. Instead, about 1,001 wstETH went into Lido’s Base-to-Ethereum bridge, which locks funds for about seven days.

So that portion is not spendable until around October 11. Meanwhile, roughly 782 wstETH stayed on Base after the drain.

PublicAML also notes that gas was funded through Tornado Cash about 2.5 hours before the attack. According to MSB Intel, a 1 wstETH bridge test ran at 09:27 UTC.

The receiving contract sits at 0xcdFE91301356da873562EF513828a60dba1F569d. On-chain trackers continue to map the redeem and bridge hashes in real time.

What the Base Vault Exploit Means Next

For now, the biggest open question is identity. The seven Safe signers remain unnamed, and the owner has not spoken publicly.

Recovery prospects also stay unclear. Because the bridged wstETH unlocks around October 11, on-chain watchers will track that window closely for any movement.

Major desks such as CoinDesk, The Block, and Bloomberg had not published dedicated coverage by evening UTC on October 4. As verified reporting grows, this Base vault exploit may shift from a security alert into a documented case study.

This article is informational and not financial advice. Always verify contract permissions and signer controls before trusting any vault with funds.