Revoking Permit2 approval

Context

With the recent PancakeSwap UI update, users may have noticed that they are prompted to sign a Permit2 approval granting type(uint256).max instead of just the intended trading amount, with an expiration set to 30 days later.

This approach is designed to enhance user experience by reducing the need to sign a Permit2 approval before every swap.

How to revoke permit2 approval

For users concerned about this broad approval, the following guide explains how to revoke it.

Step 1: Identify Key Addresses

Before proceeding, gather the necessary addresses,

Assume

User Address: 0x42571B8414c68B63A2729146CE93F23639d25399
Token Address (CAKE): 0x0e09fabb73bd3ade0a17ecc321fd13a19e81ce82
Spender (UniversalRouter): 0xd9C500DfF816a1Da21A48A732d3498Bf09dc9AEB
Permit2 contract: 0x31c2F6fcFf4F8759b3Bd5Bf0e1084A055615c768

Step 2: Verify allowance

Use a blockchain explorer or interact with the Permit2 contract directly by calling:

permit2.allowance(user, token, spender)

If approval has been granted, you will see a response similar to:

[ allowance(address,address,address) method Response ]
  // how much token allowance granted to universal router 
  amount   uint160 :  1461501637330902918203684832716283019655932542975 
  // when this approval expire 
  expiration   uint48 :  1750921247 
  nonce   uint48 :  1

This indicates that the UniversalRouter has been granted permission to spend the specified amount of CAKE tokens on behalf of the user, with the given expiration timestamp.

Step 3: Revoke the Approval

To revoke the approval, call:

permit2.approve(token, spender, amount=0, expiration=0);

This will reset the allowance and expiration, effectively revoking access.

Step 4: Confirm Revocation

Re-run the check from Step 2:

permit2.allowance(user, token, spender)

The expected response should show:

[ allowance(address,address,address) method Response ]
  amount   uint160 :  0
  // current block.timestamp 
  expiration   uint48 :  1748334096
  nonce   uint48 :  0