Safety / Signal report
The wallet approval mistake that can outlive a transaction
A wallet prompt can grant an app permission to move tokens later. Understanding approvals is one of the most practical security lessons in crypto.
Published 18 July 2026 / Updated 20 July 2026 / 5 min read
Approving a token is different from sending it, but it can authorise a later transfer.
An unlimited approval may remain active until it is revoked or replaced.
Use a separate wallet for unfamiliar apps and review permissions regularly.
The signal
Not every wallet request is a payment. Some requests ask for permission instead: permission for a smart contract to spend a particular token from your address now or later.
That permission is called an approval or allowance. It is a normal part of using many decentralised exchanges and apps. The risk comes from approving the wrong contract, granting more access than intended, or forgetting that the permission is still active.
Why the danger can be delayed
With a direct transfer, the result is usually visible straight away. An approval can look uneventful because no token needs to leave when it is signed. The authorisation remains recorded on the network, waiting for the approved contract to use it.
If the contract is malicious, compromised or designed to request excessive access, tokens can move later. That delay can make it difficult to connect a loss with a page visited days or months earlier.
Read the request, not the website
A polished website, familiar logo or urgent social post does not prove that a request is safe. The important information is in the wallet prompt: which token is involved, which contract receives permission, how much it may spend and which network you are using.
If the wallet shows an unlimited amount when you only need to use a small quantity, reduce the allowance when the interface permits it. If the contract or purpose is unclear, reject the request and verify the app through a separately found official source.
Never trust a link simply because it arrived from an account you follow. Social accounts, advertisements and search results can all point to convincing imitations.
A calmer wallet setup
Separate activities by risk. Keep long-term assets in a wallet that does not connect to unfamiliar apps. Use a different wallet, holding only what you need, for experiments and new services.
This does not make a bad approval harmless, but it limits what is exposed. A hardware wallet protects keys from leaving the device; it cannot make a permission safe if the owner approves it.
Reviewing old permissions
Token approvals can be inspected and revoked using a wallet's security tools or a reputable block explorer. Revoking is itself an on-chain transaction, so it normally requires a network fee.
MetaMask's guidance explains that revoking replaces the existing allowance with a lower value, typically zero. Review each network you have used because permissions on one network do not represent permissions on another.
Be careful when searching for an approval checker. Fake “revoke” sites are a known route to more malicious signatures. Start from your wallet provider's official help pages or a block explorer you have independently verified.
The practical move
Set a recurring reminder to review approvals on every active wallet. Remove permissions for services you no longer use, and investigate anything you do not recognise. The strongest habit is simple: pause before every signature and treat a request for permission with the same care as a request to send money.