pysec - pysec-2024-150

PYSEC-2024-150

Vulnerability from pysec - Published: 2024-02-07 17:15 - Updated: 2024-11-21 14:23

Details

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.

Severity ?

9.8 (Critical)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Impacted products

Name	purl
vyper	pkg:pypi/vyper

Aliases

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "vyper",
        "purl": "pkg:pypi/vyper"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.4.0b1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "0.1.0b1",
        "0.1.0b10",
        "0.1.0b11",
        "0.1.0b12",
        "0.1.0b13",
        "0.1.0b14",
        "0.1.0b15",
        "0.1.0b16",
        "0.1.0b17",
        "0.1.0b2",
        "0.1.0b3",
        "0.1.0b4",
        "0.1.0b5",
        "0.1.0b6",
        "0.1.0b7",
        "0.1.0b8",
        "0.1.0b9",
        "0.2.1",
        "0.2.10",
        "0.2.11",
        "0.2.12",
        "0.2.13",
        "0.2.14",
        "0.2.15",
        "0.2.16",
        "0.2.2",
        "0.2.3",
        "0.2.4",
        "0.2.5",
        "0.2.6",
        "0.2.7",
        "0.2.8",
        "0.2.9",
        "0.3.0",
        "0.3.1",
        "0.3.10",
        "0.3.10rc1",
        "0.3.10rc2",
        "0.3.10rc3",
        "0.3.10rc4",
        "0.3.10rc5",
        "0.3.2",
        "0.3.3",
        "0.3.4",
        "0.3.5",
        "0.3.6",
        "0.3.7",
        "0.3.8",
        "0.3.9"
      ]
    }
  ],
  "aliases": [
    "CVE-2024-24563",
    "GHSA-52xq-j7v9-v4v2"
  ],
  "details": "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\u0027t 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\u0027s 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.\n\nThere 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 \u003c x`, the developer will suppose that no elements on indexes `y | y \u003e= 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\u0027t be declared extremely large). However, all these the scenarios are highly unlikely. Most likely behavior is a revert on the bounds check.",
  "id": "PYSEC-2024-150",
  "modified": "2024-11-21T14:23:03.024978+00:00",
  "published": "2024-02-07T17:15:00+00:00",
  "references": [
    {
      "type": "EVIDENCE",
      "url": "https://github.com/vyperlang/vyper/security/advisories/GHSA-52xq-j7v9-v4v2"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/vyperlang/vyper/security/advisories/GHSA-52xq-j7v9-v4v2"
    },
    {
      "type": "WEB",
      "url": "https://github.com/vyperlang/vyper/blob/a1fd228cb9936c3e4bbca6f3ee3fb4426ef45490/vyper/codegen/core.py#L534-L541"
    },
    {
      "type": "WEB",
      "url": "https://github.com/vyperlang/vyper/blob/c150fc49ee9375a930d177044559b83cb95f7963/vyper/semantics/types/subscriptable.py#L127-L137"
    }
  ],
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-52XQ-J7V9-V4V2

Vulnerability from github – Published: 2024-02-07 17:27 – Updated: 2024-11-22 20:46

Summary

Vyper negative array index bounds checks

Details

Summary

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. Typically, negative integers are filtered out at runtime by the bounds checker, but small enough (i.e. large in magnitude, ex. -2**255 + 5) quantities combined with large enough arrays (at least 2**255 in length) can pass the bounds checker, resulting in unexpected behavior.

A contract search was performed, and no production contracts were found to be impacted.

Details

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. Here is an example from 0.3.10: https://github.com/vyperlang/vyper/blob/c150fc49ee9375a930d177044559b83cb95f7963/vyper/semantics/types/subscriptable.py#L127-L137

As can be seen, the validation is performed against IntegerT.any().

PoC

If the array is sufficiently large, it can be indexed with a negative value:

arr: public(uint256[MAX_UINT256])

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

For signed integers, 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): https://github.com/vyperlang/vyper/blob/a1fd228cb9936c3e4bbca6f3ee3fb4426ef45490/vyper/codegen/core.py#L534-L541

Patches

Patched in https://github.com/vyperlang/vyper/pull/3817.

Impact

There are two potential vulnerability classes: unpredictable behavior and accessing inaccessible elements.

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.
If a contract has an invariant in the form assert index < x where both index and x are signed integers, the developer might suppose that no elements on indexes y | y >= x are accessible. However, by using negative indexes this can be bypassed.

The contract search found no production contracts impacted by these two classes of issues.

Severity ?

9.8 (Critical)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "vyper"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.4.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2024-24563"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-129"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2024-02-07T17:27:58Z",
    "nvd_published_at": "2024-02-07T17:15:10Z",
    "severity": "CRITICAL"
  },
  "details": "### Summary\nArrays can be keyed by a signed integer, while they are defined for unsigned integers only. The typechecker doesn\u0027t throw when spotting the usage of an `int` as an index for an array. Typically, negative integers are filtered out at runtime by the bounds checker, but small enough (i.e. large in magnitude, ex. `-2**255 + 5`) quantities combined with large enough arrays (at least `2**255` in length) can pass the bounds checker, resulting in unexpected behavior.\n\nA contract search was performed, and no production contracts were found to be impacted.\n\n### Details\nThe typechecker allows the usage of signed integers to be used as indexes to arrays. The vulnerability is present in different forms in all versions. Here is an example from `0.3.10`:\nhttps://github.com/vyperlang/vyper/blob/c150fc49ee9375a930d177044559b83cb95f7963/vyper/semantics/types/subscriptable.py#L127-L137\n\nAs can be seen, the validation is performed against `IntegerT.any()`.\n\n### PoC\nIf the array is sufficiently large, it can be indexed with a negative value:\n```python\narr: public(uint256[MAX_UINT256])\n\n@external\ndef set(idx: int256, num: uint256):\n    self.arr[idx] = num\n```\nFor signed integers, the 2\u0027s 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):\nhttps://github.com/vyperlang/vyper/blob/a1fd228cb9936c3e4bbca6f3ee3fb4426ef45490/vyper/codegen/core.py#L534-L541\n\n### Patches\nPatched in https://github.com/vyperlang/vyper/pull/3817.\n\n### Impact\nThere are two potential vulnerability classes: unpredictable behavior and accessing inaccessible elements.\n\n1. 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.\n\n2. If a contract has an invariant in the form `assert index \u003c x` where both `index` and `x` are signed integers, the developer might suppose that no elements on indexes `y | y \u003e= x` are accessible. However, by using negative indexes this can be bypassed.\n\nThe contract search found no production contracts impacted by these two classes of issues.",
  "id": "GHSA-52xq-j7v9-v4v2",
  "modified": "2024-11-22T20:46:17Z",
  "published": "2024-02-07T17:27:58Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/vyperlang/vyper/security/advisories/GHSA-52xq-j7v9-v4v2"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2024-24563"
    },
    {
      "type": "WEB",
      "url": "https://github.com/pypa/advisory-database/tree/main/vulns/vyper/PYSEC-2024-150.yaml"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/vyperlang/vyper"
    },
    {
      "type": "WEB",
      "url": "https://github.com/vyperlang/vyper/blob/a1fd228cb9936c3e4bbca6f3ee3fb4426ef45490/vyper/codegen/core.py#L534-L541"
    },
    {
      "type": "WEB",
      "url": "https://github.com/vyperlang/vyper/blob/c150fc49ee9375a930d177044559b83cb95f7963/vyper/semantics/types/subscriptable.py#L127-L137"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Vyper negative array index bounds checks"
}

CVE-2024-24563 (GCVE-0-2024-24563)

Vulnerability from cvelistv5 – Published: 2024-02-07 17:10 – Updated: 2025-06-17 21:29

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.

Severity ?

9.8 (Critical)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CWE

CWE-129 - Improper Validation of Array Index

Assigner

GitHub_M

References

URL

Tags

	https://github.com/vyperlang/vyper/security/advis…	x_refsource_CONFIRM
	https://github.com/vyperlang/vyper/blob/a1fd228cb…	x_refsource_MISC
	https://github.com/vyperlang/vyper/blob/c150fc49e…	x_refsource_MISC

Impacted products

	Vendor	Product	Version
	vyperlang	vyper	Affected: <= 0.3.10

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "providerMetadata": {
          "dateUpdated": "2024-08-01T23:19:52.952Z",
          "orgId": "af854a3a-2127-422b-91ae-364da2661108",
          "shortName": "CVE"
        },
        "references": [
          {
            "name": "https://github.com/vyperlang/vyper/security/advisories/GHSA-52xq-j7v9-v4v2",
            "tags": [
              "x_refsource_CONFIRM",
              "x_transferred"
            ],
            "url": "https://github.com/vyperlang/vyper/security/advisories/GHSA-52xq-j7v9-v4v2"
          },
          {
            "name": "https://github.com/vyperlang/vyper/blob/a1fd228cb9936c3e4bbca6f3ee3fb4426ef45490/vyper/codegen/core.py#L534-L541",
            "tags": [
              "x_refsource_MISC",
              "x_transferred"
            ],
            "url": "https://github.com/vyperlang/vyper/blob/a1fd228cb9936c3e4bbca6f3ee3fb4426ef45490/vyper/codegen/core.py#L534-L541"
          },
          {
            "name": "https://github.com/vyperlang/vyper/blob/c150fc49ee9375a930d177044559b83cb95f7963/vyper/semantics/types/subscriptable.py#L127-L137",
            "tags": [
              "x_refsource_MISC",
              "x_transferred"
            ],
            "url": "https://github.com/vyperlang/vyper/blob/c150fc49ee9375a930d177044559b83cb95f7963/vyper/semantics/types/subscriptable.py#L127-L137"
          }
        ],
        "title": "CVE Program Container"
      },
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2024-24563",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "total"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2024-02-08T20:33:01.677566Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2025-06-17T21:29:28.634Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "vyper",
          "vendor": "vyperlang",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c= 0.3.10"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "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\u0027t 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\u0027s 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.\n\nThere 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 \u003c x`, the developer will suppose that no elements on indexes `y | y \u003e= 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\u0027t be declared extremely large). However, all these the scenarios are highly unlikely. Most likely behavior is a revert on the bounds check."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "HIGH",
            "baseScore": 9.8,
            "baseSeverity": "CRITICAL",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "HIGH",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-129",
              "description": "CWE-129: Improper Validation of Array Index",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2024-02-07T17:10:08.385Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/vyperlang/vyper/security/advisories/GHSA-52xq-j7v9-v4v2",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/vyperlang/vyper/security/advisories/GHSA-52xq-j7v9-v4v2"
        },
        {
          "name": "https://github.com/vyperlang/vyper/blob/a1fd228cb9936c3e4bbca6f3ee3fb4426ef45490/vyper/codegen/core.py#L534-L541",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/vyperlang/vyper/blob/a1fd228cb9936c3e4bbca6f3ee3fb4426ef45490/vyper/codegen/core.py#L534-L541"
        },
        {
          "name": "https://github.com/vyperlang/vyper/blob/c150fc49ee9375a930d177044559b83cb95f7963/vyper/semantics/types/subscriptable.py#L127-L137",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/vyperlang/vyper/blob/c150fc49ee9375a930d177044559b83cb95f7963/vyper/semantics/types/subscriptable.py#L127-L137"
        }
      ],
      "source": {
        "advisory": "GHSA-52xq-j7v9-v4v2",
        "discovery": "UNKNOWN"
      },
      "title": "Vyper array negative index vulnerability"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2024-24563",
    "datePublished": "2024-02-07T17:10:08.385Z",
    "dateReserved": "2024-01-25T15:09:40.209Z",
    "dateUpdated": "2025-06-17T21:29:28.634Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.1"
}

Sightings

Author	Source	Type	Date

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

Action not permitted

PYSEC-2024-150

GHSA-52XQ-J7V9-V4V2

Summary

Details

PoC

Patches

Impact

CVE-2024-24563 (GCVE-0-2024-24563)

Tags

Sightings

Nomenclature