Attacker drains up to $310K from two Safes through a leverage module the owners switched on
Two Safe multisigs lost up to $310K after an attacker impersonated a Safe to get past FlashLoopAdapter, an Aave leverage add-on the owners had enabled. Aave and Safe's core code held, so the loss fell on owners who let a module move funds without signatures.
The Investor · Invest desk
What happened
- Funded by a Morpho flash loan inside a single transaction, the attacker paid down roughly 1,300 to 1,335 WETH of the wallets' Aave debt to free their collateral.
- Collateral worth around 1,306.48 WETH came out of one Safe and a smaller sum from the other, leaving the attacker about 114.09 ETH after repaying the loan.
- Security firms SlowMist and ExVul raised alerts, and both affected Safes disabled the module right away to stop further losses.
Why it matters
- Who's exposed exposure A leveraged Safe position is only as strong as the least-audited contract allowed to touch it, so each module that can move funds needs at least the review its signer set gets.
- Who has to decide decision With FlashLoopAdapter switched off, both owners are back to running every leverage step by hand through their signers, the work the module was enabled to spare them.
- What's now possible capability Because borrowed WETH covered more than 1,300 WETH of debt for one transaction, a similar adapter bug can be exploited by someone without capital of their own, up to the size of the victim's position.
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Set the attacker's net of about 114.09 ETH [9] against the roughly 1,300 to 1,335 WETH of Aave debt it had to repay first [7], and the take is 8.5% to 8.8% of the borrowing it cleared [18]. Put the other way, about 11.4 to 11.7 ether of debt sat behind every ether the attacker kept [19]. These were thin positions, the kind a module like FlashLoopAdapter is built to assemble [5].
The victims' loss is the same gap seen from their side. Their debt was repaid in the same transaction that took their collateral [7], so what they lost is the equity between the two. Divide Crypto Briefing's $305K to $310K loss estimate [3] by 114.09 ETH [9] and you get about $2,670 to $2,720 per ether [17]. At that price the dollar figure and the attacker's net are the same sum. The report does not say what ether price it used.
The fault can sit in one of three places. The narrow answer is a single badly written adapter. Post-incident analyses cited by Crypto Briefing found that open() and close() accepted caller-controlled responses without confirming they came from a legitimate Safe [10]. According to SlowMist's account, a fake contract posing as Safe authentication got past that check [6][2]. The broad answer is Safe's design. A module with broad execution rights inherits the wallet's power, and the multisig's signature requirements do little once the module has been granted a way around them [14]. The third answer blames the flash loan for supplying the capital [15], though the borrowed WETH only mattered after the adapter had let the wrong caller in [10].
I think the narrow answer fits the evidence. The broad one is the counter-thesis that anyone holding leveraged Safe positions should keep in mind anyway. Aave released collateral because debt was repaid, as designed [11]. But the owners had given the adapter permission to operate their accounts [5], so along its code paths their multisig was protected only by the checks the adapter's authors wrote [14]. The narrow answer would be wrong if a later analysis traced the forged authentication past a check in Safe's own contracts. The analyses so far put the failed check inside FlashLoopAdapter [10][11].
What to watch
- Where the attacker's roughly 114.09 ETH goes next; a freeze or return would shrink the victims' $305K to $310K loss.
- Whether other Aave leverage adapters for Safe turn out to accept a caller's claim to be a Safe in the same way open() and close() did.
- Any change by Safe to how enabled modules can execute without signer approval, a move that would put part of the fault in the core design.
Information, not investment advice. This story is general information about companies and markets, drawn from cited reporting. It is not a recommendation to buy, sell or hold any security; check the cited sources before acting.
Clarity's read
What the record supports and how the coverage leans. The claims behind it follow.
Reality
- Evidence70
- Adoption
- Not scored
- Hype gap+12
- Incentives35
- Confidence72
Perspective Coverage
3 publishers- Builder
- Builder 38%
- Operator
- Operator 37%
- Investor
- Investor 25%
Claim ledger
Ranked by verification strength, evidence, and original report placement.
- [1]
An attacker drained two Safe multisig wallets on Ethereum on October 1, 2026, by exploiting a third-party module built to run leveraged positions on Aave v3.
- [2]
Security firm SlowMist flagged the attack and reported that the exploiter forged Safe authentication and repaid about 1,300 WETH of Aave debt to unlock the wallets' collateral.
- [3]
Combined victim losses are estimated between $305K and $310K.
- [4]
Neither Aave v3 nor Safe's core infrastructure was compromised; the weak link was the FlashLoopAdapter, a module the victims had enabled on their own wallets.
- [5]
The FlashLoopAdapter is designed to help users build leveraged positions on Aave v3 and gets limited permission to operate the account so the owner does not have to do every step by hand.
- [6]
The attacker deployed a fake contract that impersonated Safe authentication, letting them slip past the module's access controls and steer its execution paths to move assets out of the two multisigs.
- [7]
With the borrowed funds, the attacker paid down roughly 1,300 to 1,335 WETH of Aave debt held by the wallets, freeing the collateral behind it.
- [8]
From one Safe, the attacker pulled collateral worth around 1,306.48 WETH; a smaller sum came out of the second wallet.
- [9]
After repaying the flash loan, the attacker's net profit was approximately 114.09 ETH.
- [10]
Post-incident analyses traced the flaw to the module's open() and close() functions: weak validation of caller-controlled responses, with the module accepting answers from whoever called it without properly confirming they came from a legitimate Safe.
- [11]
For Aave, the protocol worked as designed: debt was repaid, so collateral was released; the failure sat entirely in the adapter that decided who was allowed to trigger those actions.
- [12]
The whole operation ran in a single transaction, starting with a WETH flash loan sourced from Morpho.
- [13]
SlowMist and ExVul raised alerts after the attack, and both affected Safes disabled the vulnerable module right away to stop further losses.
- [14]
A module with broad execution rights over a wallet inherits that wallet's power; if the module has a bug, the multisig's signature requirements do not help much because the module was already granted a way around them.
- [15]
Flash loans mean attackers can bring enormous temporary capital to any flaw, so even narrow bugs can unlock large balances.
- [16]
For users running leveraged strategies through third-party tooling, a position's security is only as strong as the least-audited contract with permission to touch it; any module that can move funds deserves the same scrutiny as the wallet's signer set, arguably more, since it can act without collecting signatures.
- [17]
The $305K to $310K loss estimate divided by the 114.09 ETH net implies roughly $2,670 to $2,720 per ether.
- [18]
The attacker's net profit equals 8.5% to 8.8% of the Aave debt repaid.
- [19]
About 11.4 to 11.7 WETH of debt was repaid for each ETH of the attacker's net profit.
Sources
3 independent publishers whose own reporting we read for this story.
- cointelegraph.comAave founder says V3 unaffected after third-party adapter exploit drains $305K
1 article · October 2, 2026
- cryptobriefing.comAave v3 exploit drains up to $310K after Safe module attack
1 article · October 1, 2026
- dev.toFlashLoopAdapter Exploit: How a Caller-Authentication Flaw in Aave V3 Safe Module Drained $305K
1 article · October 2, 2026
Topics and entities
Topics
- Smart-contract wallet modules
- DeFi Security