CVE-2023-46247

Vyper has incorrect storage layout for contracts containing large arrays

HIGH
7.5
CVSS Score
Published: December 13, 2023 at 07:39 PM UTC
Updated: June 17, 2026 at 06:30 AM UTC
1 product affected across 1 vendorVyper

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Severity
HIGH7.5
Exploit prediction
EPSS 0.7%

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

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 0.3.8
Affected range stops below 0.3.8, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

CVSS

7.5HIGHGitHub_M
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
HIGH
Availability
NONE
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-193CWE-682

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