CVE-2020-37289 PUBLISHED

Vyper before 0.3.1 Improper Input Validation of uint8 Interface Return Values

Assigner: VulnCheck
Reserved: 20.10.2026 Published: 21.10.2026 Updated: 21.10.2026

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.

CVSS Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
CVSS Score: 6.3

Exploitability Metrics		Vulnerable System Impact Metrics		Subsequent System Impact Metrics
Attack Vector	Network	Confidentiality	None	Confidentiality	None
Attack Complexity	Low	Integrity	Low	Integrity	None
Attack Requirements	Present	Availability	None	Availability	None
Privileges Required	None
User Interaction	None

CVSS 4.0

CVSS Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
CVSS Score: 3.7

Attack Vector	Network	Scope	Unchanged
Attack Complexity	High	Confidentiality Impact	None
Privileges Required	None	Integrity Impact	Low
User Interaction	None	Availability Impact	None

CVSS 3.1

Product Status

Vendor	vyperlang
Product	vyper
Versions	Default: unaffected affected from 0 to 0.3.1 (excl.) Version 0.3.1 is unaffected

CVE-2020-37289 PUBLISHED

Vyper before 0.3.1 Improper Input Validation of uint8 Interface Return Values

Metrics

Product Status

Credits

References

Problem Types