{"id":"CVE-2021-48019","state":"PUBLISHED","title":"Vyper before 0.2.9 Incorrect RETURNDATASIZE in create_forwarder_to Proxies","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.","publishedAt":"2026-10-21T00:36:18.960Z","updatedAt":"2026-10-27T21:35:59.282Z","severity":{"score":6.3,"label":"Medium","version":"4.0","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","source":"VulnCheck"},"assigner":"VulnCheck","products":["vyperlang vyper"],"affected":[{"vendor":"vyperlang","product":"vyper","packageURL":"pkg:pypi/vyper","defaultStatus":"unaffected","versions":[{"version":"0","status":"affected","lessThan":"0.2.9","versionType":"python"},{"version":"0.2.9","status":"unaffected","versionType":"python"}]}],"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"],"weaknesses":["CWE-805"],"ingestedAt":"2026-10-29T19:49:22.269Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2021/48xxx/CVE-2021-48019.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2021-48019","state":"PUBLISHED","datePublished":"2026-10-21T00:36:18.960Z","dateUpdated":"2026-10-27T21:35:59.282Z","assignerShortName":"VulnCheck","assignerOrgId":"83251b91-4cc7-4094-a5c7-464a1b83ea10","dateReserved":"2026-10-20T21:51:44.816Z"},"containers":{"cna":{"title":"Vyper before 0.2.9 Incorrect RETURNDATASIZE in create_forwarder_to Proxies","descriptions":[{"lang":"en","value":"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. 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