{"id":"CVE-2020-37289","title":"Vyper before 0.3.1 Improper Input Validation of uint8 Interface Return Values","summary":"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 man…","severity":"low","cvss":3.7,"cvssVector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N","cvssSource":"cna","cwe":["CWE-20"],"vendor":"vyperlang","product":"vyper","affected":["vyper < 0.3.1"],"published":"2026-10-21","updated":"2026-10-21","sourceUpdated":"2026-10-21T00:36:17.573Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2020-37289","references":[{"url":"https://github.com/vyperlang/vyper/security/advisories/GHSA-mr6r-mvw4-736g","label":"GitHub Security Advisory (GHSA-mr6r-mvw4-736g)"},{"url":"https://www.vulncheck.com/advisories/vyper-before-0.3.1-improper-input-validation-of-uint8-interface-return-values","label":"VulnCheck Advisory: Vyper before 0.3.1 Improper Input Validation of uint8 Interface Return Values"}],"tags":["cve.org"],"ingestedAt":"2026-10-21T01:37:08.049Z","slug":"CVE-2020-37289","body":"## Overview\n\nVyper 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.\n\n## Affected\n\n- `vyper < 0.3.1`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":20,"depthScoreParts":{"impact":20.4,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}