# CVE-2023-46247: incorrect storage layout for contracts containing large arrays

Source: https://junglewise.ai/threats/cve-2023-46247-incorrect-storage-layout-for-contracts-containing-large-arrays  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2023-12-13  
License: CC BY 4.0 with a link back

CVE-2023-46247 · Severity: low · CVSS 3.1 · Published 2023-12-13

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.

Technologies: [vyper (PyPI)](https://junglewise.ai/threats/technologies/vyper). Vendors: [PyPI](https://junglewise.ai/threats/vendors/pypi).

## Quick answers

**Is CVE-2023-46247 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2023-46247 being exploited in the wild.

**How severe is CVE-2023-46247?** Low severity, with a CVSS score of 3.1, published 13 December 2023.

**Which products and versions are affected?** vyper (PyPI) ECOSYSTEM:introduced=0,fixed=0.3.8, GIT:introduced=0,fixed=0bb7203b584e771b23536ba065a6efda457161bb|ECOSYSTEM:introduced=0,fixed=0.3.8.

**Is there a fix for CVE-2023-46247?** Yes. vyper (PyPI): upgrade to 0.3.8 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**Am I affected by CVE-2023-46247?** Check whether you run vyper (PyPI) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- vyper (PyPI): upgrade to 0.3.8 or later

  ```sh
  pip install "vyper>=0.3.8"
  ```


## Affected products

- vyper (PyPI) ECOSYSTEM:introduced=0,fixed=0.3.8, GIT:introduced=0,fixed=0bb7203b584e771b23536ba065a6efda457161bb|ECOSYSTEM:introduced=0,fixed=0.3.8

## Identifiers

- CVE-2023-46247
- GHSA-6m97-7527-mh74
- PYSEC-2023-307

## Related threats

- [Vyper memory corruption in nested function calls and tuples](https://junglewise.ai/threats/vyper-memory-corruption-using-function-calls-within-tuples-nested-calls-c0689acb)
- [Vyper stack corruption in complex type argument passing](https://junglewise.ai/threats/vyper-call-stack-corruption-when-passing-complex-type-containing-non-3deb0c30)
- [Vyper return statement in nested for loops causes revert](https://junglewise.ai/threats/vyper-return-inside-for-loop-more-than-1-level-deep-ee8a193d)
- [PYSEC-2026-2028 - Vyper's `slice()` may elide side-effects when output length is 0](https://junglewise.ai/threats/cve-2025-47774-vyper-s-slice-may-elide-side-effects-when-output-length-is-0)
- [PYSEC-2026-2029 - Vyper's `concat()` builtin may elide side-effects for zero-length arguments](https://junglewise.ai/threats/cve-2025-47285-vyper-s-concat-builtin-may-elide-side-effects-for-zero-length)