ghsa-3whq-64q2-qfj6
Vulnerability from github
Published
2024-04-25 19:50
Modified
2024-06-18 15:08
Severity ?
5.3 (Medium) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Summary
vyper performs double eval of raw_args in create_from_blueprint
Details

Summary

Using the create_from_blueprint builtin can result in a double eval vulnerability when raw_args=True and the args argument has side-effects.

A contract search was performed and no vulnerable contracts were found in production. In particular, the raw_args variant of create_from_blueprint was not found to be used in production.

Details

It can be seen that the _build_create_IR function of the create_from_blueprint builtin doesn't cache the mentioned args argument to the stack: https://github.com/vyperlang/vyper/blob/cedf7087e68e67c7bfbd47ae95dcb16b81ad2e02/vyper/builtins/functions.py#L1847

As such, it can be evaluated multiple times (instead of retrieving the value from the stack).

PoC

The vulnerability is demonstrated in the following boa test: ``` vyper src1 = """ c: uint256 """ deployer = """ created_address: public(address) deployed: public(uint256)

@external def get() -> Bytes[32]: self.deployed += 1 return b''

@external def create_(target: address): self.created_address = create_from_blueprint(target, raw_call(self, method_id("get()"), max_outsize=32), raw_args=True, code_offset=3) """

Factory = b.loads_partial(src1) c = Factory.deploy_as_blueprint()

c2 = b.loads(deployer, b'') c2.create_(c) c2.deployed() `` The output ofc2.deployed()is2althoughcreate_was called only once and the value was initialized to0`.

Patches

Patched in https://github.com/vyperlang/vyper/pull/3976.

Impact

No vulnerable production contracts were found. Additionally, double evaluation of side-effects should be easily discoverable in client tests. As such, the impact is low.

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{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "vyper"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.4.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2024-32647"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-95"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2024-04-25T19:50:50Z",
    "nvd_published_at": "2024-04-25T18:15:08Z",
    "severity": "MODERATE"
  },
  "details": "### Summary\nUsing the `create_from_blueprint` builtin can result in a double eval vulnerability when `raw_args=True` and the `args` argument has side-effects. \n\nA contract search was performed and no vulnerable contracts were found in production. In particular, the `raw_args` variant of `create_from_blueprint` was not found to be used in production.\n\n### Details\nIt can be seen that the `_build_create_IR` function of the `create_from_blueprint` builtin doesn\u0027t cache the mentioned `args` argument to the stack: https://github.com/vyperlang/vyper/blob/cedf7087e68e67c7bfbd47ae95dcb16b81ad2e02/vyper/builtins/functions.py#L1847\n\nAs such, it can be evaluated multiple times (instead of retrieving the value from the stack).\n\n### PoC\nThe vulnerability is demonstrated in the following `boa` test:\n``` vyper\nsrc1 = \"\"\"\nc: uint256\n\"\"\"\ndeployer = \"\"\"\ncreated_address: public(address)\ndeployed: public(uint256)\n\n@external\ndef get() -\u003e Bytes[32]:\n    self.deployed += 1\n    return b\u0027\u0027\n\n@external\ndef create_(target: address):\n    self.created_address = create_from_blueprint(target, raw_call(self, method_id(\"get()\"), max_outsize=32), raw_args=True, code_offset=3)\n\"\"\"\n\nFactory = b.loads_partial(src1)\nc = Factory.deploy_as_blueprint()\n\nc2 = b.loads(deployer, b\u0027\u0027)\nc2.create_(c)\nc2.deployed()\n```\nThe output of `c2.deployed()` is `2` although `create_` was called only once and the value was initialized to `0`.\n\n### Patches\nPatched in https://github.com/vyperlang/vyper/pull/3976.\n\n### Impact\nNo vulnerable production contracts were found. Additionally, double evaluation of side-effects should be easily discoverable in client tests. As such, the impact is `low`.\n",
  "id": "GHSA-3whq-64q2-qfj6",
  "modified": "2024-06-18T15:08:56Z",
  "published": "2024-04-25T19:50:50Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/vyperlang/vyper/security/advisories/GHSA-3whq-64q2-qfj6"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2024-32647"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/vyperlang/vyper"
    },
    {
      "type": "WEB",
      "url": "https://github.com/vyperlang/vyper/blob/cedf7087e68e67c7bfbd47ae95dcb16b81ad2e02/vyper/builtins/functions.py#L1847"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "vyper performs double eval of raw_args in create_from_blueprint"
}


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