CVE-2023-42443

What it is

Vyper is a Pythonic Smart Contract Language for the Ethereum Virtual Machine (EVM). In version 0.3.9 and prior, under certain conditions, the memory used by the builtins `raw_call`, `create_from_blueprint` and `create_copy_of` can be corrupted. For `raw_call`, the argument buffer of the call can be corrupted, leading to incorrect `calldata` in the sub-context. For `create_from_blueprint` and `create_copy_of`, the buffer for the to-be-deployed bytecode can be corrupted, leading to deploying incorrect bytecode. Each builtin has conditions that must be fulfilled for the corruption to happen. For `raw_call`, the `data` argument of the builtin must be `msg.data` and the `value` or `gas` passed to the builtin must be some complex expression that results in writing to the memory. For `create_copy_of`, the `value` or `salt` passed to the builtin must be some complex expression that results in writing to the memory. For `create_from_blueprint`, either no constructor parameters should be passed to the builtin or `raw_args` should be set to True, and the `value` or `salt` passed to the builtin must be some complex expression that results in writing to the memory. As of time of publication, no patched version exists. The issue is still being investigated, and there might be other cases where the corruption might happen. When the builtin is being called from an `internal` function `F`, the issue is not present provided that the function calling `F` wrote to memory before calling `F`. As a workaround, the complex expressions that are being passed as kwargs to the builtin should be cached in memory prior to the call to the builtin.

At a glance

Exploitability

Can be exploited over the network without logging in. High risk of data exposure, data tampering, service disruption.

Exploit odds

0.8% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2023-09-18 21:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-17 06:23 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.8% in the next 30 days (EPSS).
• Severity: 8.1 HIGH (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2023-09-18 21:16 UTC

Last modified

2026-06-17 06:23 UTC

Exploit probability

0.8% · EPSS, next 30 days

Weakness

CWE-787 · Out-of-bounds write

Record status

Modified

Affected

• Vyperlang Vyper < 0.3.10

Attack profile CVSS 3.1 · 8.1

Attack vector

Network

Complexity

High

Privileges needed

None

User interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2023-42443.md and follow it. Check whether this project is affected by CVE-2023-42443. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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