{"cve":"CVE-2021-48019","nvd":{"published":"2026-10-21T01:17:19.130","modified":"2026-10-22T17:00:33.203","status":"Deferred","description":"Vyper before 0.2.9 deploys forwarder proxies through the built-in create_forwarder_to function that report a fixed 4096-byte RETURNDATASIZE rather than the actual return data size. Calls through these proxies can yield corrupted data when a function returns more than 4096 bytes without return data sanitation, and fail strict return-size checks such as SafeERC20.safeTransfer.","cvss_v4":{"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:L/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:L","score":4.8},"cwes":["CWE-805"],"references":["https://github.com/vyperlang/vyper/security/advisories/GHSA-375m-5fvv-xq23","https://www.vulncheck.com/advisories/vyper-before-0.2.9-incorrect-returndatasize-in-create-forwarder-to-proxies"],"products":[],"source":"nvd","synced_at":"2026-10-23T16:39:26.291718493+00:00"},"epss":{"cve":"CVE-2021-48019","score":0.00248,"percentile":0.15913,"date":"2026-10-25"},"kev":null,"osv":[{"id":"GHSA-375m-5fvv-xq23","url":"https://osv.dev/vulnerability/GHSA-375m-5fvv-xq23","summary":"VVE-2021-0002: Incorrect `returndatasize` when using simple forwarder proxies deployed prior to EIP-1167 adoption","modified":"2026-10-24T02:56:08.111958927Z","packages":[{"ecosystem":"PyPI","name":"vyper","purl":"pkg:pypi/vyper","ranges":["<0.2.9"],"fixed":["0.2.9"]}]}],"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."]}