Improper Validation of Array Index Affecting vyper package, versions [0,0.4.0)


Severity

Recommended
0.0
critical
0
10

CVSS assessment made by Snyk's Security Team. Learn more

Threat Intelligence

Exploit Maturity
Proof of Concept
EPSS
0.12% (48th percentile)

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  • Snyk IDSNYK-PYTHON-VYPER-6231774
  • published8 Feb 2024
  • disclosed7 Feb 2024
  • creditcyberthirst

Introduced: 7 Feb 2024

CVE-2024-24563  (opens in a new tab)
CWE-129  (opens in a new tab)

How to fix?

Upgrade vyper to version 0.4.0 or higher.

Overview

vyper is a Pythonic Smart Contract Language for the EVM.

Affected versions of this package are vulnerable to Improper Validation of Array Index due to the handling of array indexes. An attacker can cause unpredictable behavior or access inaccessible elements by using signed integers as indexes for arrays, which bypasses the bounds checker under certain conditions.

Note:

This is only exploitable if the array is sufficiently large and the negative index is small enough in magnitude to pass the bounds checker.

PoC

arr: public(uint256[MAX_UINT256])

@external
def set(idx: int256, num: uint256):
    self.arr[idx] = num

CVSS Scores

version 3.1