FlashLoopAdapter: how a spoofable caller check cost two Safe wallets 114 ETH

What happened

On 1 October 2026, at about 15:08 UTC, one Ethereum transaction emptied about 114 ETH, roughly $305,000, from two Safe multisig wallets. The wallets belonged to users of FlashLoopAdapter, a small custom module for opening and closing leveraged positions on Aave v3.

This was not a hack of Aave and it was not a hack of Safe. Aave founder Stani Kulechov said on X, as quoted by CryptoSlate: "This is not Aave v3 contract, it's third party external adapter built on top of Aave, zero effect on Aave v3."

The incident is small by the standards of September 2026. It is worth the space because the mistake is a very common one.

What is confirmed

Two security teams have published analysis, SlowMist and Verichains, and their accounts line up.

• When and how much. 1 October 2026, about 15:08 UTC, about 114.09 ETH, around $305,000, from two Safe wallets on Ethereum mainnet, in a single transaction (Verichains; SlowMist figure matches).
• Who was hit. Two wallets that had enabled the adapter as a module. Verichains says the module was deployed on 16 July and both wallets enabled it the next day, and that no other Safe appears in its history. It reads this as private yield tooling rather than a public product. That is an inference.
• Debt repaid. SlowMist says about 1,300 WETH of debt was repaid during the attack to unlock the collateral. A Morpho WETH flash loan funded this, according to PublicAML and Verichains.
• What was not affected. Aave v3's core contracts and Safe's core contracts, according to both analysts and to Kulechov.

We have not found a statement from the module's developers.

How it worked

A Safe is a shared wallet. Its owners can enable a module, a separate contract that is allowed to move the wallet's assets without collecting signatures. That is a powerful permission, and it means the module is the real lock on the door.

FlashLoopAdapter's job was to repeat a cycle: supply collateral to Aave, borrow against it, and loop, to build up a leveraged position, then reverse the cycle to close it.

Two weaknesses combined, according to SlowMist and Verichains.

It asked the caller to vouch for itself. To decide whether a caller was a legitimate Safe, the module asked the caller whether the module was enabled. A real Safe answers truthfully. But any contract can imitate that answer and say yes, so the check protected nothing. The attacker deployed a fake "Safe" that always answered yes.

It let the caller choose where its calls went. The module also accepted, from the caller, the address of the exchange router to call and the exact instructions to send. The attacker pointed the "router" at a victim's real Safe and sent instructions asking that Safe to run commands for its enabled module. Since the victim had enabled the module, the Safe obeyed.

A flash loan, borrowed in the same transaction, paid off the victims' Aave debt so their collateral could be withdrawn. Verichains stresses that the flash loan amplified the attack but was not the cause.

We deliberately do not describe the exact calls.

What is not known

• Who the attacker is. Neither analyst names anyone.
• Whether any funds were recovered. We found no report either way.
• Who runs the module and whether other Safes enabled it. Verichains' reading is that only two did.
• Whether the developers have retired the contract or notified the affected owners.

Where sources disagree

There is little disagreement. The loss is reported as about $305,000 by Verichains and as $305,000 to $310,000 by one tracker. SlowMist and Verichains both put it at 114.09 ETH, and the dollar range is a matter of ETH price. Dates match, with some outlets reporting 2 October because SlowMist posted its alert then.

Lessons

• Never authenticate a caller by asking the caller. A view function on the caller's own address can be faked by any contract. Check the address against a list you control.
• Do not let a caller choose a call target and its data. If a module forwards arbitrary calls, it can be pointed at anything that trusts it.
• A Safe module is root. Treat what it can do as the wallet's whole balance. Review modules as you would a signing key.
• Flash loans are the amplifier, not the cause. Do not stop at "it used a flash loan". Ask what let the attacker's code run.
• Private tooling still holds real money. "Only we use it" does not replace a review.

What users should do

If you use any Safe module, list which modules are enabled on your wallets and who wrote them. Disable modules you do not use or cannot review.

If you ever enabled FlashLoopAdapter, check that your positions and collateral are as you expect. Contact the developers through official channels.

Sources: SlowMist and Verichains, with a statement from Aave founder Stani Kulechov as quoted by CryptoSlate and a note from PublicAML on the flash loan. We did not link them. The module has no official project page that we could find, so none is cited here.