What Does Unlimited Wallet Authorization Mean: Which Permissions Are Most Dangerous

"Unlimited authorization" means allowing a project or smart contract to transfer a specific token from your wallet an unlimited number of times, without your further consent.

This is one of the most common and severe risks in Web3. You haven't initiated a transfer, yet your assets could be silently drained in the background.

Prerequisites

• You have connected to a DApp (decentralized application) and clicked "Approve" or "Authorize" in your wallet.
• You know which tokens you hold in that wallet.
• You can access permission management tools online, such as Revoke.cash.

How Unlimited Authorization Works

Under the standard ERC-20 protocol, if you want to trade USDT on a DEX, you must first authorize the contract to spend your USDT. To reduce user friction, most projects set the approval limit to the maximum value (2^256-1), i.e., "unlimited".

The most dangerous part is that with an unlimited allowance, the project can call the transferFrom function at any time to transfer the entire balance of that token from your address. This requires no additional signature or private key from you. According to statistics from 2025, unlimited approval abuse accounted for 67% of asset losses caused by poor permission management.

The 3 Most Dangerous Permission Types

1. Unlimited Token Approval (ERC20 Approve): Authorizes a contract to transfer a specific token (e.g., USDT, ETH) from your wallet without limit. This is the most direct target of phishing sites, which trick users into approving on fake DeFi or airdrop pages.

2. NFT SetApprovalForAll: This is a common approval function on NFT marketplaces. If you grant this to a malicious contract, the attacker can transfer all NFTs of that collection from your wallet. Legitimate marketplaces like OpenSea often request this permission, but their contracts are secure; the danger lies in being tricked into authorizing a counterfeit phishing address.

3. Hidden Data Authorization: Scammers may ask you to check "address availability" and trick you into filling in specific Data fields when sending a transaction. It looks like you are sending 0 tokens, but in fact the on-chain transaction calls the approve function, granting the scammer permission to spend your tokens.

Common Misconceptions

Many people believe that simply "disconnecting the wallet" will cancel the authorization. In reality, disconnecting only severs the front-end display; the on-chain approval you granted to that contract remains valid, and the contract can still move your assets. True revocation requires initiating an on-chain revoke transaction to modify the state.

Risk Reminder: The core of approval phishing is tricking you into signing a transaction that appears normal. Once the approval is granted, even a hardware wallet cannot provide extra protection, because the attacker has obtained a legitimate on-chain permission that does not require your private key signature. If you suspect you have signed a malicious approval, or if you haven't used a DApp for a long time, immediately check and revoke using tools like Revoke.cash.

How to Revoke and Verify

Go to Revoke.cash, connect your wallet and select the corresponding network. The page will list all approval records for that address. Click the "Revoke" button, pay a small gas fee to complete the on-chain operation. Once the transaction is confirmed, the permission for that address is removed. You can verify by checking the "Token Approvals" page on a blockchain explorer (like Etherscan) that the record has disappeared. The whole process takes about 5 minutes.