Vulnerabilities > CVE-2024-24563 - Improper Validation of Array Index vulnerability in Vyperlang Vyper

CVSS 9.8 - CRITICAL

Attack vector

NETWORK

Attack complexity

LOW

Privileges required

NONE

Confidentiality impact

HIGH

Integrity impact

HIGH

Availability impact

HIGH

network

low complexity

vyperlang

CWE-129

critical

NVD

Published: 2024-02-07

Updated: 2024-02-15

Summary

Vyper is a Pythonic Smart Contract Language for the Ethereum Virtual Machine. Arrays can be keyed by a signed integer, while they are defined for unsigned integers only. The typechecker doesn't throw when spotting the usage of an `int` as an index for an array. The typechecker allows the usage of signed integers to be used as indexes to arrays. The vulnerability is present in different forms in all versions, including `0.3.10`. For ints, the 2's complement representation is used. Because the array was declared very large, the bounds checking will pass Negative values will simply be represented as very large numbers. As of time of publication, a fixed version does not exist. There are three potential vulnerability classes: unpredictable behavior, accessing inaccessible elements and denial of service. Class 1: If it is possible to index an array with a negative integer without reverting, this is most likely not anticipated by the developer and such accesses can cause unpredictable behavior for the contract. Class 2: If a contract has an invariant in the form `assert index < x`, the developer will suppose that no elements on indexes `y | y >= x` are accessible. However, by using negative indexes, this can be bypassed. Class 3: If the index is dependent on the state of the contract, this poses a risk of denial of service. If the state of the contract can be manipulated in such way that the index will be forced to be negative, the array access can always revert (because most likely the array won't be declared extremely large). However, all these the scenarios are highly unlikely. Most likely behavior is a revert on the bounds check.

Vulnerable Configurations

Part	Description	Count
Application	Vyperlang Vyperlang Vyper 0.0.4 Vyperlang Vyper 0.1.0 Vyperlang Vyper 0.2.0 Vyperlang Vyper 0.2.1 Vyperlang Vyper 0.2.2 Vyperlang Vyper 0.2.3 Vyperlang Vyper 0.2.4 Vyperlang Vyper 0.2.5 Vyperlang Vyper 0.2.6 Vyperlang Vyper 0.2.7 Vyperlang Vyper 0.2.8 Vyperlang Vyper 0.2.9 Vyperlang Vyper 0.2.10 Vyperlang Vyper 0.2.11 Vyperlang Vyper 0.2.12 Vyperlang Vyper 0.2.13 Vyperlang Vyper 0.2.14 Vyperlang Vyper 0.2.15 Vyperlang Vyper 0.2.16 Vyperlang Vyper 0.3.0 Vyperlang Vyper 0.3.1 Vyperlang Vyper 0.3.2 Vyperlang Vyper 0.3.3 Vyperlang Vyper 0.3.4 Vyperlang Vyper 0.3.5 Vyperlang Vyper 0.3.6 Vyperlang Vyper 0.3.7 Vyperlang Vyper 0.3.8 Vyperlang Vyper 0.3.9 Vyperlang Vyper 0.3.10	46

Common Weakness Enumeration (CWE)

CWE-129 - Improper Validation of Array Index

Common Attack Pattern Enumeration and Classification (CAPEC)

Overflow Buffers
Buffer Overflow attacks target improper or missing bounds checking on buffer operations, typically triggered by input injected by an attacker. As a consequence, an attacker is able to write past the boundaries of allocated buffer regions in memory, causing a program crash or potentially redirection of execution as per the attackers' choice.

Summary

Vulnerable Configurations

Common Weakness Enumeration (CWE)

Common Attack Pattern Enumeration and Classification (CAPEC)

References