CVE-2023-32058: Vyper vulnerable to integer overflow in loop
(updated )
Due 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.
In the following example, calling test
returns 354
, meaning that the variable a
did store 354
a value out of bound for the type uint8
.
@external
def test() -> uint16:
x:uint8 = 255
a:uint8 = 0
for i in range(x, x+100):
a = i
return convert(a,uint16)
The 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.
thanks to @trocher for reporting
References
- github.com/advisories/GHSA-6r8q-pfpv-7cgj
- github.com/pypa/advisory-database/tree/main/vulns/vyper/PYSEC-2023-78.yaml
- github.com/vyperlang/vyper
- github.com/vyperlang/vyper/commit/3de1415ee77a9244eb04bdb695e249d3ec9ed868
- github.com/vyperlang/vyper/security/advisories/GHSA-6r8q-pfpv-7cgj
- nvd.nist.gov/vuln/detail/CVE-2023-32058
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