Incorrect Type Conversion or Cast Affecting vyper package, versions [0.3.8,0.4.0b1)
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Test your applications- Snyk ID SNYK-PYTHON-VYPER-6674047
- published 26 Apr 2024
- disclosed 25 Apr 2024
- credit trocher
Introduced: 25 Apr 2024
CVE-2024-32481 Open this link in a new tabHow to fix?
Upgrade vyper to version 0.4.0b1 or higher.
Overview
vyper is a Pythonic Smart Contract Language for the EVM.
Affected versions of this package are vulnerable to Incorrect Type Conversion or Cast due to an incorrect assertion in the code generation for the range statement. If a call goes through the loop while supplying a negative start, the execution will revert.
Note:
The issue arises when start is signed, instead of using sle, le is used and start is interpreted as an unsigned integer for the comparison. If it is a negative number, its 255th bit is set to 1 and is hence interpreted as a very large unsigned integer making the assertion always fail.
PoC
@external
def foo():
x:int256 = min_value(int256)
# revert when it should not since we have the following assertion that fails:
# [assert, [le, min_value(int256), max_value(int256) + 1 - 10]],
for i in range(x, x + 10):
pass