Not a U.S. government website. NDD is an independent vulnerability database by Volerion and is not affiliated with or endorsed by NIST or NVD.

CVE-2020-37289 Details

ANALYZED

This CVE record has been analyzed and enriched by NVDAPI.com as an independent party.

Description

Vyper before 0.3.1 lacks a uint8 type, allowing interface return values declared as uint8, such as ERC20.decimals(), to be stored in uint256 variables without bounds checking. Malicious contracts can return values greater than 255 to manipulate or bypass contract logic that relies on these values.

Metrics

CVSS 3.x Severity and Vector Strings:

VolerionCVSS-B:5.3 MEDIUMVector:CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

CNA: [email protected]CVSS-B:3.7 LOWVector:CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N

References to Advisories, Solutions, and Tools

By selecting these links, you will be leaving this site. These are references gathered from the official CVE record and are not endorsed by Volerion.

URL	Source(s)	Tag(s)
https://github.com/vyperlang/vyper/security/advisories/GHSA-mr6r-mvw4-736g	[email protected]	AdvisoryRemedyVendor
https://www.vulncheck.com/advisories/vyper-before-0.3.1-improper-input-validation-of-uint8-interface-return-values	[email protected]	AdvisoryRemedy

Weakness Enumeration

CWE-ID	CWE Name	Source
CWE-20	Improper Input Validation	[email protected]

Affected Products

Product	Versions
Vyper	< 0.3.1 (semver)
CPE cpe:2.3:a:vyper_project:vyper:::::::: Remediation Upgrade: 0.3.1moderate effort Mitigation:low effort Verify that the value returned by any interface that specifies a uint8 type is within the range of a uint8 integer (0-255). For example: ```python ... # returns uint8, but we implicitly cast to uint256 without checking decimals: uint256 = ERC20(_token).decimal() # FIX: Insert this line assert decimals < 256 ... ```

Product

Versions

Vyper

< 0.3.1 (semver)

CPE

cpe:2.3:a:vyper_project:vyper:*:*:*:*:*:*:*:*

Remediation

Upgrade: 0.3.1moderate effort
Mitigation:low effort
Verify that the value returned by any interface that specifies a uint8 type is within the range of a uint8 integer (0-255). For example: ```python ... # returns uint8, but we implicitly cast to uint256 without checking decimals: uint256 = ERC20(_token).decimal() # FIX: Insert this line assert decimals < 256 ... ```

Change History

2 change records found show changes

Date	Action	Recorded By
Oct 28, 2026	CVE Modified	CISA-ADP
Oct 21, 2026	New CVE Received	[email protected]