{"id":"CVE-2023-32058","aliases":["GHSA-6r8q-pfpv-7cgj","PYSEC-2023-78"],"url":"https://o3.security/vulnerability/CVE-2023-32058","summary":"Vyper vulnerable to integer overflow in loop","details":"### Impact\n\nDue to missing overflow check for loop variables, by assigning the iterator of a loop to a variable, it is possible to overflow the type of the latter.\n\nIn the following example, calling `test` returns `354`, meaning that the variable `a` did store `354` a value out of bound for the type `uint8`.\n\n```Vyper\n@external\ndef test() -> uint16:\n    x:uint8 = 255\n    a:uint8 = 0\n    for i in range(x, x+100):\n        a = i\n    return convert(a,uint16)\n```\n\nThe issue seems to happen only in loops of type `for i in range(a, a + N)` as in loops of type `for i in range(start, stop)` and `for i in range(stop)`, the compiler is able to raise a `TypeMismatch` when trying to overflow the variable.\n\nthanks to @trocher for reporting\n\n### Patches\n\npatched in 3de1415ee77a9244eb04bdb695e249d3ec9ed868\n\n### Workarounds\n\n ","published":"2023-05-11T20:55:35.195Z","modified":"2026-10-28T02:31:00.448239504Z","cvss":{"score":7.5,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},"epss":null,"cisaKev":null,"exploitsKnown":1,"affectedPackages":[{"ecosystem":"PyPI","name":"vyper","fixedVersion":"0.3.8"}],"fix":{"url":"https://github.com/vyperlang/vyper/commit/3de1415ee77a9244eb04bdb695e249d3ec9ed868","label":"vyperlang/vyper@3de1415"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/32xxx/CVE-2023-32058.json"},{"type":"ADVISORY","url":"https://github.com/vyperlang/vyper/security/advisories/GHSA-6r8q-pfpv-7cgj"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2023-32058"},{"type":"FIX","url":"https://github.com/vyperlang/vyper/commit/3de1415ee77a9244eb04bdb695e249d3ec9ed868"},{"type":"WEB","url":"https://github.com/pypa/advisory-database/tree/main/vulns/vyper/PYSEC-2023-78.yaml"},{"type":"PACKAGE","url":"https://github.com/vyperlang/vyper"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-10-28T02:31:00.448239504Z"}}