{"id":"CVE-2023-32058","aliases":["GHSA-6r8q-pfpv-7cgj","PYSEC-2023-78"],"title":"Vyper vulnerable to integer overflow in loop","summary":"Vyper vulnerable to integer overflow in loop","severity":"high","cvss":7.5,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","vendor":"vyper","product":"vyper","ecosystem":"pip","affected":["vyper < 0.3.8"],"patched":["vyper 0.3.8"],"published":"2023-05-12","updated":"2026-09-10","sourceUpdated":"2026-09-10T03:50:01.254556464Z","source":"OSV","sourceUrl":"https://osv.dev/vulnerability/GHSA-6r8q-pfpv-7cgj","references":[{"url":"https://github.com/vyperlang/vyper/security/advisories/GHSA-6r8q-pfpv-7cgj"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2023-32058"},{"url":"https://github.com/vyperlang/vyper/commit/3de1415ee77a9244eb04bdb695e249d3ec9ed868"},{"url":"https://github.com/pypa/advisory-database/tree/main/vulns/vyper/PYSEC-2023-78.yaml"},{"url":"https://github.com/vyperlang/vyper"}],"tags":["osv","pip"],"epss":0.00913,"epssPercentile":0.58026,"ingestedAt":"2026-09-12T03:13:01.667Z","slug":"CVE-2023-32058","body":"## Overview\n\n### 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 \n\n## Affected packages\n\n- `vyper < 0.3.8`\n\n## Remediation\n\nUpgrade to a patched release:\n\n- `vyper 0.3.8`","depth":"twilight","depthScore":41,"depthScoreParts":{"impact":41.3,"likelihood":0.2,"exploitation":0,"ransomware":0},"changes":[]}