CVE-2026-114118

Deferred Deferred - Pending Action

Vulnerability in Vyper Smart Contracts Allows Blueprint Exploitation

Publication date: 2026-10-21

Last updated on: 2026-10-27

Assigner: VulnCheck

Description

Vyper 0.3.4 through 0.5.0b1 computes the remaining blueprint size in create_from_blueprint by uint256 subtraction without first checking that code_offset is below the blueprint's code size, so a huge offset wraps to a small positive value. An attacker controlling code_offset can make a factory deploy contracts with no runtime code, potentially trapping ETH and tokens.

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Meta Information

Published

2026-10-21

Last Modified

2026-10-27

Generated

2026-11-10

AI Q&A

2026-10-21

EPSS Evaluated

2026-11-08

NVD

CVE-2026-114118

EUVD

EUVD-2026-106921

Affected Vendors & Products

Vendor	Product	Version / Range
vyperlang	vyper	0.3.4

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-681	When converting from one data type to another, such as long to integer, data can be omitted or translated in a way that produces unexpected values. If the resulting values are used in a sensitive context, then dangerous behaviors may occur.

Attack-Flow Graph

Executive Summary

This vulnerability affects Vyper versions 0.3.4 through 0.5.0b1. The create_from_blueprint function fails to validate the code_offset parameter before calculating remaining blueprint size using uint256 subtraction. An attacker can provide a large offset that wraps around to a small positive value due to unsigned integer underflow, causing the function to deploy contracts with no runtime code.

Detection Guidance

To detect this vulnerability, inspect Vyper smart contracts using versions 0.3.4 through 0.5.0b1 for the create_from_blueprint function. Check if code_offset validation is missing or improperly implemented. Review contract deployment logs for contracts with empty runtime bytecode deployed via create_from_blueprint.

Impact Analysis

An attacker exploiting this can make a factory deploy contracts with empty runtime bytecode instead of the intended blueprint. This can trap ETH and tokens in inaccessible addresses, disrupt contract initialization, and violate assumptions about deployed contracts. Users sending funds to these addresses may lose access to their assets.

Compliance Impact

This vulnerability does not directly affect compliance with GDPR, HIPAA, or similar standards as it pertains to a technical flaw in Vyper's contract deployment mechanism rather than data protection or privacy controls. However, if exploited, it could lead to unauthorized access or loss of funds, which may indirectly impact compliance with financial or operational regulations depending on the affected system's context.

Mitigation Strategies

Upgrade Vyper to a patched version beyond 0.5.0b1. If using create_from_blueprint, validate code_offset < extcodesize(target) using an unsigned comparison before subtraction. Alternatively, use a fixed valid offset like code_offset=3 as a workaround.

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