CVE-2023-46247
HIGHCVE-2023-46247 is a high-severity (CVSS 7.5) CWE-193 vulnerability in vyper. O3 Security confirms whether CVE-2023-46247 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Vyper has incorrect storage layout for contracts containing large arrays
Blast Radius
vyperReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.
Description
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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | vyper | all versions | 0.3.8 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for vyper. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update vyper to 0.3.8 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-46247 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2023-46247 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2023-46247. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2023-46247 in your dependencies?
O3 detects CVE-2023-46247 across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.