Vyper Smart Contract Language Vulnerability Allows Attackers to Access Data Beyond Bounds

CVSScvssV3_1: 9.8

Vyper is a popular smart contract programming language for developing decentralized applications on the Ethereum blockchain. Researchers discovered a vulnerability in versions 0.3.10 and earlier that could allow attackers to access data outside the intended bounds of an array.

The vulnerability lies in the slice() function not properly validating if the start and length arguments provided would cause an overflow when added together. By passing non-literal values, an attacker could craft the arguments in a way that exceeds the actual size of the array.

This would let an attacker read or modify data beyond what was intended to be accessible in memory, storage or calldata. They could view private variables, modify the length of arrays to corrupt their contents, or even crash applications.

If you have any smart contracts written in Vyper versions affected, it’s recommended to upgrade to the latest version immediately. Developers should also audit any use of slice() to ensure arguments can’t be controlled by external users. Being vigilant about input validation is key to prevent overflows and improper data access in smart contracts.

Staying on top of software updates and conducting security reviews regularly can help protect applications from vulnerabilities like this. Let this serve as a reminder of the importance of input validation and bounds checking in any programming that processes untrusted data.