---
title: "Update on Similar Match Contract Verification"
description: "Similar Match Contract Verification is a useful tool for verifying commonly reused contracts. However, the re-verification tool was previously exploited, leading to this update."
url: https://info.etherscan.com/update-on-similar-match-contract-verification/
tags: ["Developer"]
published: 2022-04-05
updated: 2026-06-21
---

# Update on Similar Match Contract Verification

[Similar Match](https://info.etherscan.com/types-of-contract-verification/) is a convenient tool to display source code and Read/Write contract capabilities for contracts with similar bytecode, but different constructor arguments.

This enables similar contracts that are commonly reused_,_ such as libraries, factories_,_ and proxies_,_ to be verified without individually verifying each contract.

## Source Code Comment Attacks

The Similar Match re-verification tool was previously exploited by malicious actors performing verification with the correct constructor arguments, however injecting comments, graffiti art, and renaming files.

![](https://info.etherscan.com/update-on-similar-match-contract-verification/images/2024/06/image-3.png)

A sample contract verification that was vandalized

To mitigate such an exploit, we temporarily **restricted** the degree of Similar Match re-verification as we developed a more secure method to protect re-verification.

## Similar Match Contract Verification Whitelist

We've introduced a whitelist for smart contract authors to resubmit verification to update the contracts to Full Match.

This process is similar to Token Information Update to prove contract ownership. Contract authors/ developers would need to [verify their contract address ownership](https://info.etherscan.com/how-to-verify-address-ownership/) with an Etherscan account, which you may [sign up](https://etherscan.io/register) for free here.

You may then write to us via a [Contact Us](https://etherscan.io/contactus) form to be included for Similar Match Contract Verification.

Once your Etherscan account has been whitelisted for Similar Match Contract Verification, you will be able to proceed to the [source code verification page](https://etherscan.io/verifyContract) to reverify a similar matched contract. The process from there is the same as verifying a regular contract.

If your account has not had Similar Match updating enabled, you will encounter an error message, which you may request access via a [Contact Us](https://etherscan.io/contactus) form.

![](https://info.etherscan.com/update-on-similar-match-contract-verification/images/2024/06/image-4.png)