TwentyOne

Summary

The use of a floating pragma version specifier (^0.8.13) in the Solidity smart contract introduces a vulnerability where future compiler updates could potentially introduce unexpected changes or bugs, leading to unpredictable contract behavior.

Vulnerability Details

The floating pragma (^0.8.13) allows the contract to be compiled with any version of Solidity from 0.8.13 up to (but not including) 0.9.0. While this ensures compatibility with newer versions, it also means that if a newer compiler version introduces:

• Breaking changes: Even minor changes in behavior could affect the contract.

• Undiscovered bugs: New compiler versions may have bugs that can be exploited.

• Security updates: Developers may assume the deployed contract has incorporated critical security patches, which might not be true if the pragma was used inconsistently.

This flexibility introduces uncertainty about which compiler version is being used for deployment, leading to potential security issues.

Impact

Using a floating pragma can result in:

• Unintended Behavior: The contract may not function as expected if compiled with a version that alters Solidity's behavior or introduces subtle changes.

• Deployment Risks: Future deployments using updated versions of the compiler could inadvertently introduce vulnerabilities or inconsistencies.

• Exploitability: Attackers may exploit differences in behavior caused by the use of different compiler versions.

Tools Used

Manual review

Recommendations

Replace the floating pragma with an explicit version to ensure deterministic behavior. For example :

pragma solidity 0.8.13;