A user connects their Web3 wallet to a decentralized exchange, a lending protocol, or an NFT marketplace. A transaction preview appears showing the action they initiated: swap tokens, deposit collateral, or mint an NFT. What many users do not examine closely is a second, hidden transaction embedded in the same approval flow: a token allowance grant that gives the protocol unlimited permission to move those tokens on the user’s behalf. That permission, once confirmed, cannot be easily revoked without additional transactions and gas fees. It persists indefinitely until the user explicitly cancels it. Understanding how this permissions model works, and why it poses a real financial risk, is not optional knowledge for anyone holding assets in a Web3 wallet.
Token approvals are a structural feature of Ethereum and EVM-compatible blockchains, not a flaw in any individual wallet. However, the way a wallet displays, explains, and helps users manage those permissions determines whether users make informed decisions or blindly grant access they do not understand. Rabby Wallet’s approach to approval transparency and transaction preview is designed to surface these risks before a user signs. That design matters because the alternative—signing without examining what permissions are being granted—has led to the theft of millions of dollars in tokens, NFTs, and liquidated positions.
How token approvals work on Ethereum and EVM chains
Every token transfer on Ethereum follows a permission model. If you own USDC, USDT, DAI, or any ERC-20 token, you directly control your private key and the ability to move those tokens. However, when you interact with a smart contract—a decentralized exchange, lending protocol, or automated market maker—that contract cannot simply pull tokens from your wallet. It must first receive explicit permission in the form of an allowance. This permission is set via an “approve” transaction that increases the number of tokens that a specific contract address can spend from your wallet.
The allowance model exists for security reasons. It prevents a contract you have never interacted with from accessing your tokens. It also means that if a contract is compromised or behaves maliciously, it can only steal tokens up to the allowance amount. In theory, this creates a defensive boundary. In practice, most users and many protocols grant allowances that are unlimited in size, denominated in blockchain terms as a very large number such as 2^256 – 1. This converts the permission from “you may move 1000 USDC” to “you may move as many tokens as I ever hold.” Once that permission is granted, it remains active until the user submits a separate approve transaction setting the allowance to zero.
The permission is tied to the contract address, not to any temporal limit. A user may approve a decentralized exchange to move their USDC on Ethereum, Polygon, Arbitrum, and other networks separately because each chain has its own state. An approval given years ago, for a protocol that has been abandoned or acquired, still grants permission to any code running at that address. This is why security researchers regularly publish lists of “high-risk” token approvals: contracts that received unlimited permissions from thousands of users and now pose a supply-chain risk if the contract itself is ever compromised, upgraded, or exploited by an attacker who gains control of the private keys needed to modify it.
From a blockchain perspective, an allowance is simply a number stored in the token contract’s state. The wallet cannot prevent a malicious contract from stealing all approved tokens—that authority belongs to the smart contract code itself. What a wallet can do is inform the user about what permission they are granting before they sign, and provide tools to monitor and revoke permissions after the fact. This is where the design of transaction preview becomes practically important.
Why unlimited approvals have become a de facto standard
Most decentralized protocols request unlimited approvals by default. A user swapping tokens on Uniswap, depositing collateral on Aave, or trading NFTs on OpenSea will typically see an approval transaction in their signing flow without explicit notice that it is unlimited. The reason is pragmatic: unlimited approvals require only one signing event per token per protocol, while limited approvals force the user to re-approve whenever their balance grows above the original allowance amount. For a protocol handling millions of users and transaction attempts, requesting infinite allowance reduces friction and support costs.
Users have largely accepted this trade-off because they assume that reputable protocols will not abuse the permission and that the approval process is more or less invisible—just another step in the transaction flow. This assumption held when the set of active protocols was smaller and fewer contracts were considered “trusted.” As the ecosystem expanded, the same addresses accumulated approvals from hundreds of thousands of users. An attacker stealing the private keys to a high-value contract address could theoretically drain millions in approved tokens across all users who had granted that contract permission.
The incentive to abuse an approval is also indirect but real. A compromised protocol could be used to steal approved tokens. A protocol could be acquired by a bad actor. A security vulnerability in the contract code could be exploited. Or an insider with access to the contract’s upgrade mechanisms could redirect tokens to a personal address. The longer an approval remains active, the larger the window in which any of these scenarios could occur. A user who approved a protocol five years ago has no way to know whether that contract’s security posture has degraded or whether the team behind it still controls the keys.
The ecosystem has begun to recognize this problem. Solutions include approval management services, decentralized protocols that use alternative permission models such as allowance delegation, and wallet-level tools that make approvals more visible and revocable. However, the default behavior of most protocols remains unchanged: request unlimited permission, and rely on users to understand the risk and manage their own approvals.
How Rabby Wallet makes approval risks visible
Rabby Wallet addresses the approval transparency problem through its transaction preview system. Before a user signs any transaction—including an approval—the wallet simulates the action and displays what will actually happen. For an approval transaction, this means showing the contract address, the token being approved, and the allowance amount being granted. Crucially, Rabby highlights whether the allowance is unlimited and flags this as a potential risk requiring user attention.
This approach serves multiple purposes. First, it makes the approval visible at all, rather than burying it as one step in a multi-step interaction. A user connecting to a dApp and seeing a “swap 100 USDC for ETH” action should also see the corresponding approval transaction and understand that two separate blockchain operations are occurring. Second, it quantifies the risk. Rather than asking users to trust that “reputable” protocols would never abuse an approval, Rabby presents the specific terms: this contract can move an unlimited amount of this token from your wallet, indefinitely, until you revoke it.
The wallet also provides tools to revoke approvals without returning to the original protocol. Users can navigate to Rabby’s approvals management interface, view all active allowances across all tokens and chains, and revoke any of them with a single transaction. This reduces the friction of revoking old approvals and helps users clean up permissions granted years earlier to protocols they no longer use. A user might have approved Uniswap v2 on Ethereum in 2021, then moved to Uniswap v3, leaving the old approval active indefinitely. Rabby makes revoking that forgotten approval straightforward.
The transaction preview feature extends beyond approvals. When a user interacts with a smart contract that will execute a swap, borrow tokens, or perform any other action, Rabby simulates the transaction and displays the expected outcome. If slippage, fees, or market conditions change between the preview and the actual signing, the user can see the difference and choose whether to proceed. This transparency is particularly valuable for DeFi interactions because contract behavior can be nonlinear: the actual output of a swap, the health factor after a borrow, or the reward amount from a staking action can differ significantly from initial expectations. A simulation catches many of these discrepancies before the transaction is finalized.
The attack surface created by an unmanaged approval
An unlimited approval creates a specific attack surface that has been exploited repeatedly. The most direct vector is a dApp exploit: the user connects their wallet to a protocol that has a vulnerability. The attacker executes a transaction that appears to be a normal trade or interaction but actually calls the user’s previously granted approvals to transfer approved tokens to a personal address. The user signed an approval weeks or months earlier and forgot about it. The attacker never needs the user’s private key; the approval already granted the necessary permission.
A second vector is protocol compromise. If a decentralized exchange, lending protocol, or NFT marketplace is hacked or the team’s private keys are stolen, an attacker with control of the contract can drain all approved tokens. This has happened multiple times in Web3 history, affecting users who were simply using legitimate protocols. The users did nothing wrong; they held their private keys securely and used a protocol with good reputation. But the approvals they granted years earlier became liabilities when the protocol’s security was breached.
A third vector is social engineering. An attacker sends a phishing email or message claiming to be from a protocol the user has approved. They convince the user to visit a fake website or sign a malicious transaction. If the user’s approval to the legitimate protocol is still active, the attacker can submit a transaction that uses that existing approval to steal tokens without the user ever visiting the real protocol. The user’s mistake was trusting the wrong link, not using an insecure wallet; the attack simply leveraged an existing permission.
A fourth, slower vector is contract upgrade risk. Many protocols use upgradeable smart contracts. The team can modify the contract’s behavior without changing its address. If the team goes bad, is acquired, or the project’s governance is compromised, an upgrade could introduce code that steals from approved users. This risk is often invisible: a user who approved the contract years ago may not monitor governance changes and may not realize that the contract’s code no longer does what they intended.
Web3 security depends on granular permission control
Best practice for managing approvals involves three rules. First, grant only what is necessary. If you are swapping 100 USDC for ETH once, there is no reason to grant unlimited permission. If the protocol supports limited approvals, use that instead. Some wallets and newer protocols such as sites.google.com/rabby-wallet-extension.com/rabby-wallet-official-site provide interfaces to propose finite allowances even when a protocol requests unlimited ones. Second, revoke approvals regularly. Set a calendar reminder to audit your active approvals on your most-used chains every few months. Revoke any approvals to protocols you no longer use, to contracts that are deprecated or superseded, or to services you do not trust. Third, compartmentalize. Use separate wallets for different risk profiles: one for long-term holding on a hardware wallet, one for active DeFi trading, one for NFT experimentation. This limits the blast radius if one wallet is compromised or one protocol is exploited.
The wallet’s role in this process is to make each step feasible. Transaction preview prevents users from blindly granting approvals they did not examine. Approval management interfaces make revocation straightforward rather than requiring a return to the original protocol. Hardware wallet integration means that a user can store their primary private key on an air-gapped device and only sign transactions on a trusted screen, then approve those transactions from a mobile or desktop interface. None of these features eliminates the need for user judgment, but they reduce the friction of making secure decisions.
The alternative—assuming that protocols are always trustworthy and that compromises will never happen—has failed repeatedly. High-profile protocols have been exploited, upgrades have introduced vulnerabilities, and private keys have been stolen. Users who had granted unlimited approvals suffered losses that users with limited approvals or revoked permissions did not. The lesson is straightforward: assume that at least one protocol you have approved will eventually be compromised, and plan accordingly. An approval is not a one-time trust decision; it is an ongoing permission that should be audited and revoked as circumstances change.
Practical workflows for safe approval management
A user preparing to interact with a new DeFi protocol should follow a deliberate sequence. Start by researching the protocol’s security history, audits, and team. Check whether their approval is requested, and understand whether it is limited or unlimited. Review Rabby Wallet’s transaction preview to see the exact approval being granted before signing. If the protocol accepts limited approvals, propose a finite amount—perhaps double the transaction size to allow for price movement without re-approval. Sign the approval transaction separately from the actual swap, deposit, or interaction. Review the signed approval in an explorer or wallet history to confirm it was recorded correctly. Only then proceed to the actual protocol interaction.
After using a protocol, maintain a mental inventory of active approvals. Every few months, navigate to Rabby’s approval management section and review all allowances across all tokens and chains. Identify protocols you no longer use, contracts that have been superseded, or services you have lost confidence in. Revoke those approvals in a batch transaction if the wallet supports it, paying the network’s current gas fee. This cost is negligible compared to the cost of a single token theft. Mark your calendar to repeat this audit quarterly or after major events in the Web3 ecosystem, such as high-profile protocol compromises or governance changes in protocols you have approved.
For high-value holdings or active trading, consider using a hardware wallet such as a Ledger or Trezor integrated with Rabby Wallet. The hardware wallet holds the private key offline and signs transactions only when the user explicitly approves on the device’s screen. An attacker who compromises your computer or browser cannot forge signatures without the hardware device present. Approvals granted from a hardware wallet carry the same permission risks, but the attacker’s ability to sign new transactions on your behalf is eliminated. This model is most valuable for users managing significant assets or making frequent DeFi interactions where the risk of a dApp exploit or phishing attempt is higher.
The difference between approval risks and wallet security
It is important to distinguish between the risks created by approvals and the security features of the wallet itself. A non-custodial wallet like Rabby that stores private keys locally, encrypts them, supports biometric authentication, and allows offline storage provides strong protection against unauthorized access to the wallet. However, a secure wallet cannot prevent a user from granting an approval to a malicious contract, nor can it revoke permissions on behalf of the user. The wallet’s job is to inform and enable; the user’s job is to make informed decisions.
This separation of concerns is often misunderstood. Users sometimes assume that if they are using a “secure” wallet, they do not need to worry about approvals. Conversely, users sometimes blame the wallet if they lose tokens through a compromise protocol, as if the wallet should have prevented the approval from being granted in the first place. The reality is that Web3 security is shared: the wallet protects the private key, the user decides what contracts to trust, and the protocol must live up to that trust. A transaction preview feature helps bridge the gap by making sure the user is aware of what they are doing, but the final responsibility for granting an approval rests with the user.
As Web3 matures, approval management will likely improve further. Alternative permission models such as permit signatures and allowance delegation offer ways to grant temporary or limited permissions without the current all-or-nothing structure. Wallets will likely add more granular controls, warnings, and automation around approvals. But for the foreseeable future, unlimited approvals will remain the default behavior of most protocols, and users will remain responsible for managing the risks they create. Understanding how approvals work, why they pose a risk, and how to audit and revoke them is not optional; it is foundational to using any EVM-compatible wallet safely.
Frequently asked questions
If I grant an unlimited approval to a protocol and then stop using it, does the approval automatically expire?
No. An approval remains active indefinitely until you explicitly revoke it. The only way to cancel an approval is to submit a separate transaction setting the allowance to zero. This is why auditing and revoking old approvals regularly is important; a protocol you used years ago still has permission to move your tokens even if you have not visited it in years.
Can Rabby Wallet prevent me from granting an approval to a malicious contract?
Rabby can inform you about what approval you are granting through transaction preview, and it will flag unlimited allowances as a potential risk. However, the wallet cannot determine whether a contract is malicious or trustworthy; only you can make that judgment based on research, audits, and the protocol’s reputation. The wallet’s role is to make the approval visible and enable informed decision-making, not to block potentially dangerous contracts.
Is it safe to use protocols that request unlimited approvals?
Unlimited approvals are a common trade-off for convenience, and many reputable protocols request them. The risk is manageable if you audit your approvals regularly, revoke those you no longer need, and only interact with protocols you have researched and trust. Use a hardware wallet for high-value holdings to add an additional layer of security. The key is making approvals a part of your ongoing security practice, not a one-time action you forget about.
