Incorrect Type Conversion or Cast Affecting vyper package, versions [0.3.8,0.4.0b1)
Threat Intelligence
Snyk has a proof-of-concept or detailed explanation of how to exploit this vulnerability.
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-PYTHON-VYPER-6674047
- published26 Apr 2024
- disclosed25 Apr 2024
- credittrocher
Introduced: 25 Apr 2024
CVE-2024-32481 (opens in a new tab)How 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