CVE-2023-46247

Advisory

Vyper, a Pythonic language for Ethereum Virtual Machine (EVM) smart contracts, had an issue where contracts with large arrays might underallocate the number of slots they need by one. This issue was addressed in version 0.3.8, which corrected a calculation that could produce a rounding error. The calculation, math.ceil(type_.size_in_bytes / 32), could overestimate or underestimate the number of slots needed. The bug is referenced as CVE-2023-46247.
https://github.com/vyperlang/vyper/security/advisories/GHSA-6m97-7527-mh74

Affected package

Affected versions

Fixed versions

Vulnerability changelog

Vyper is a Pythonic Smart Contract Language for the Ethereum Virtual Machine (EVM). Contracts containing large arrays might underallocate the number of slots they need by 1. Prior to v0.3.8, the calculation to determine how many slots a storage variable needed used `math.ceil(type_.size_in_bytes / 32)`. The intermediate floating point step can produce a rounding error if there are enough bits set in the IEEE-754 mantissa. Roughly speaking, if `type_.size_in_bytes` is large (> 2**46), and slightly less than a power of 2, the calculation can overestimate how many slots are needed by 1. If `type_.size_in_bytes` is slightly more than a power of 2, the calculation can underestimate how many slots are needed by 1. This issue is patched in version 0.3.8. See CVE-2023-46247.


MISC:https://github.com/vyperlang/vyper/blob/6020b8bbf66b062d299d87bc7e4eddc4c9d1c157/vyper/semantics/validation/data_positions.py#L197: https://github.com/vyperlang/vyper/blob/6020b8bbf66b062d299d87bc7e4eddc4c9d1c157/vyper/semantics/validation/data_positions.py#L197
MISC:https://github.com/vyperlang/vyper/commit/0bb7203b584e771b23536ba065a6efda457161bb: https://github.com/vyperlang/vyper/commit/0bb7203b584e771b23536ba065a6efda457161bb
MISC:https://github.com/vyperlang/vyper/security/advisories/GHSA-6m97-7527-mh74: https://github.com/vyperlang/vyper/security/advisories/GHSA-6m97-7527-mh74

Resources

• https://github.com/vyperlang/vyper/blob/6020b8bbf66b062d299d87bc7e4eddc4c9d1c157/vyper/semantics/validation/data_positions.py#L197
• https://github.com/vyperlang/vyper/commit/0bb7203b584e771b23536ba065a6efda457161bb
• https://github.com/vyperlang/vyper/security/advisories/GHSA-6m97-7527-mh74
• https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-46247