Two Safe wallets drained about 114 ETH through FlashLoopAdapter module exploit

Two Safe multisig wallets on Ethereum lost roughly 114.09 ETH after an attacker exploited an access-control flaw in SlowMist’s incident listing for FlashLoopAdapter, a third-party module used to manage leveraged positions. The security firm’s writeup points to the module’s authorization check as the weak point, not Safe itself or Aave’s core contracts.

According to the incident details, the module trusted a caller-supplied Safe authentication check in a way that could be spoofed through a fake Safe contract. That let the attacker route calls through the module and interact with the affected wallets as if the authorization had passed. The attack sequence also used a Morpho WETH flash loan to repay debt and unlock collateral before the borrowed funds were settled.

How the module-level check was abused

SlowMist said FlashLoopAdapter’s open() and close() logic relied on ISafe(msg.sender).isModuleEnabled(address(this)), which could be made to return true by a malicious contract. In practice, that meant the security boundary was the enabled module itself, not the lending protocol underneath it.

The reported loss was tied to two Safe wallets that had enabled the module. One wallet was used to repay debt and unlock collateral, while the second also lost assets through the same path. The affected balances were moved through the exploit flow before the attacker’s borrowed liquidity was returned.

The incident is another reminder that DeFi risk often sits in the integrations around major protocols rather than in the protocol core. In this case, the vulnerable component was a third-party adapter layered on top of Safe and Aave-related looping mechanics.