Avalanche Safe Multisig Drained Of ~$7.45M Via Stale Token Approvals

A 2-of-7 Safe multisig on Avalanche C-Chain holding roughly $7.45M of trading inventory was emptied in a single block on 26 October 2026, according to Panda Security. A DeFiHackLabs proof-of-concept entry identifies the Safe as 0x631fca4a73aee699638634479132452ef354b9b8 and lists the drained assets as 3,078,123.68 USDC, 351,374.08 WAVAX, 183.74 WETH.e and 10.77 BTC.b. The funds left through four token approvals the Safe itself had signed seven months earlier. On 7 March 2026 the Safe executed a batch granting unlimited allowances for WAVAX, USDC, WETH.e and BTC.b to 0x3725bd4d175283108156c3f15f86e1c51266155d (Avalanche), an address that had no code on the network. The DeFiHackLabs entry says the approvals were never revoked. It also says the address is the 13th CREATE output of a Safe CreateCall instance, itself deterministically deployed via the Safe Singleton Factory. Because an ERC20 approval is granted to an address rather than a specific caller, whoever first occupies that address and calls transferFrom can spend the approvals. The DeFiHackLabs entry states that the original attacker transaction (0xf1f8...1289) reverted after an MEV bot front-ran it with an identical drain transaction (0xf88a...7ed5). Panda Security says the bot's transaction landed first in the same block. According to BlockintAI's reading of the logs, the bot moved 3,090,123.58 USDC, 350,375.86 WAVAX, 181.98 WETH.e and 10.79 BTC.b out of the Safe. These figures differ slightly from the proof-of-concept's measured basket, which left the Safe holding zero of all four assets. Panda Security's analysis states that no signer key was stolen and no signer was phished. Panda Security reports that the bot returned most of the assets the next day in exchange for a bounty. On 27 October one of the Safe's owner addresses agreed on-chain to let the bot keep 42,500 WAVAX, about $371K per Defimon. BlockintAI observed the return of all USDC, WETH.e and BTC.b plus 307,834.86 WAVAX, with the bounty remaining in the holding wallet. CryptoTimes, writing earlier the same day, described the negotiation as still in progress, so the final settlement figures reflect BlockintAI's reading of the chain at the time of its report. Wallet and multisig users can reduce this risk by reviewing token approvals regularly with an allowance checker and revoking any that are no longer needed. Avoid unlimited allowances where a fixed amount will do. Before approving an address, confirm that it is a deployed, verified contract on the explorer, since an empty address can later be occupied by someone else. Teams that manage treasuries through multisigs should include approval hygiene in their routine reviews.