{"cve":"CVE-2020-37289","nvd":{"published":"2026-10-21T01:17:18.830","modified":"2026-10-22T17:00:33.203","status":"Deferred","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.","cvss_v4":{"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","score":6.3},"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N","score":3.7},"cwes":["CWE-20"],"references":["https://github.com/vyperlang/vyper/security/advisories/GHSA-mr6r-mvw4-736g","https://www.vulncheck.com/advisories/vyper-before-0.3.1-improper-input-validation-of-uint8-interface-return-values"],"products":[],"source":"nvd","synced_at":"2026-10-23T16:39:26.291718493+00:00"},"epss":{"cve":"CVE-2020-37289","score":0.00261,"percentile":0.17762,"date":"2026-10-25"},"kev":null,"osv":[{"id":"GHSA-mr6r-mvw4-736g","url":"https://osv.dev/vulnerability/GHSA-mr6r-mvw4-736g","summary":"Vyper interfaces returning integer types less than 256 bits can be manipulated if uint256 is used","modified":"2026-10-24T02:56:09.508994586Z","packages":[{"ecosystem":"PyPI","name":"vyper","purl":"pkg:pypi/vyper","ranges":["<=0.1.0b16"],"fixed":[]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}