CVE-2023-30629: Vyper Incorrect Success Value Returned Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-w9g2-3w7p-72g9",
  "modified" : "2024-11-19T16:31:34Z",
  "published" : "2023-04-24T22:33:52Z",
  "aliases" : [ "CVE-2023-30629" ],
  "summary" : "Incorrect success value returned in vyper",
  "details" : "### Background\nDuring the audit of [Lido's Gate Seals](https://github.com/lidofinance/gate-seals) code [statemind](https://statemind.io) team identified a weird behavior of the code that uses `raw_call`: https://github.com/lidofinance/gate-seals/blob/051593e74df01a4131c485b4fda52e691cd4b7d8/contracts/GateSeal.vy#L164 .\n\nConstruction like this:\n```vyper\nsuccess = raw_call(\n    sealable,\n    _abi_encode(SEAL_DURATION_SECONDS, method_id=method_id(\"pauseFor(uint256)\")),\n    revert_on_failure=False\n)\n```\nwas not fully documented: https://docs.vyperlang.org/en/v0.3.7/built-in-functions.html#raw_call .\n\nThe documentation says that: if `max_outsize=0` it should return nothing and then it says that if `revert_on_failure=False` it should return a `success` flag in the tuple of response, but what if `max_outsize=0`  and `revert_on_failure=False`.\n\n<img width=\"715\" alt=\"image\" src=\"https://user-images.githubusercontent.com/22330612/232125364-d2b3bbac-0b4f-40cb-80ff-f55d8eafef44.png\">\n\n So the team started researching what exactly happened in that case, after some research we found that the Vyper compiler generates the wrong bytecode in that case, it generates the sequence:\n```\nCALL // call\nMLOAD // MLOAD is wrong since the CALL result is already stored in the stack\n```\n\n### Impact\nExample of buggy code:\n```vyper\n@external\ndef returnSome(calling: address, a: uint256) -> bool:\n    success: bool = false\n    success = raw_call(\n        calling,\n        _abi_encode(a, method_id=method_id(\"a(uint256)\")),\n        revert_on_failure=False\n        )\n```\n\nany contract that uses the `raw_call` with `revert_on_failure=False` and `max_outsize=0` receives the wrong response from `raw_call`. Depending on the memory garbage, the result can be either `True` or `False`.\n\n### Patches\nFix by @charles-cooper https://github.com/vyperlang/vyper/commit/851f7a1b3aa2a36fd041e3d0ed38f9355a58c8ae\n\n### Workarounds\nThe simple workaround is always to put  `max_outsize>0`.\nWorkaround example https://github.com/lidofinance/gate-seals/pull/5/files\n\n### References\nLido's fix: https://github.com/lidofinance/gate-seals/pull/5/files\n",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N"
  }, {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "vyper"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0.3.1"
      }, {
        "fixed" : "0.3.8"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/vyperlang/vyper/security/advisories/GHSA-w9g2-3w7p-72g9"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2023-30629"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/lidofinance/gate-seals/pull/5/files"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/vyperlang/vyper/commit/851f7a1b3aa2a36fd041e3d0ed38f9355a58c8ae"
  }, {
    "type" : "WEB",
    "url" : "https://docs.vyperlang.org/en/v0.3.7/built-in-functions.html#raw_call"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/lidofinance/gate-seals/blob/051593e74df01a4131c485b4fda52e691cd4b7d8/contracts/GateSeal.vy#L164"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/pypa/advisory-database/tree/main/vulns/vyper/PYSEC-2023-131.yaml"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/vyperlang/vyper"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-670" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2023-04-24T22:33:52Z",
    "nvd_published_at" : "2023-04-24T22:15:10Z"
  }
}