{"id":"GHSA-5jrj-52x8-m64h","summary":"vyper performs multiple eval of `sqrt()` argument built in","details":"### Summary\nUsing the `sqrt` builtin can result in multiple eval evaluation of side effects when the argument has side-effects. The bug is more difficult (but not impossible!) to trigger as of 0.3.4, when the unique symbol fence was introduced (https://github.com/vyperlang/vyper/pull/2914).\n\nA contract search was performed and no vulnerable contracts were found in production.\n\n### Details\nIt can be seen that the `build_IR` function of the `sqrt` builtin doesn't cache the argument to the stack: \nhttps://github.com/vyperlang/vyper/blob/4595938734d9988f8e46e8df38049ae0559abedb/vyper/builtins/functions.py#L2151\n\nAs such, it can be evaluated multiple times (instead of retrieving the value from the stack).\n\n### PoC\nWith at least Vyper version `0.2.15+commit.6e7dba7` the following contract:\n```vyper\nc: uint256\n\n@internal\ndef some_decimal() -\u003e decimal:\n    self.c += 1\n    return 1.0\n\n@external\ndef foo() -\u003e uint256:\n    k: decimal = sqrt(self.some_decimal())\n    return self.c\n```\npasses the following test:\n```solidity\n// SPDX-License-Identifier: MIT\npragma solidity \u003e=0.8.13;\n\nimport \"../../lib/ds-test/test.sol\";\nimport \"../../lib/utils/Console.sol\";\nimport \"../../lib/utils/VyperDeployer.sol\";\n\nimport \"../ITest.sol\";\n\ncontract ConTest is DSTest {\n    VyperDeployer vyperDeployer = new VyperDeployer();\n\n    ITest t;\n\n    function setUp() public {\n        t = ITest(vyperDeployer.deployContract(\"Test\"));\n    }\n\n    function testFoo() public {\n        uint256 val = t.foo();\n        console.log(val);\n        assert (val == 4);\n    }\n}\n```\n \n### Patches\nPatched in https://github.com/vyperlang/vyper/pull/3976.\n\n### Impact\nNo vulnerable production contracts were found.","aliases":["CVE-2024-32649","PYSEC-2024-209"],"modified":"2026-06-10T17:14:19.090635025Z","published":"2024-04-25T19:50:16Z","database_specific":{"cwe_ids":["CWE-95"],"severity":"MODERATE","github_reviewed":true,"github_reviewed_at":"2024-04-25T19:50:16Z","nvd_published_at":"2024-04-25T18:15:09Z"},"references":[{"type":"WEB","url":"https://github.com/vyperlang/vyper/security/advisories/GHSA-5jrj-52x8-m64h"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2024-32649"},{"type":"WEB","url":"https://github.com/vyperlang/vyper/pull/2914"},{"type":"WEB","url":"https://github.com/pypa/advisory-database/tree/main/vulns/vyper/PYSEC-2024-209.yaml"},{"type":"PACKAGE","url":"https://github.com/vyperlang/vyper"}],"affected":[{"package":{"name":"vyper","ecosystem":"PyPI","purl":"pkg:pypi/vyper"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.4.0"}]}],"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","0.4.0b1","0.4.0b2","0.4.0b3","0.4.0b4","0.4.0b5","0.4.0b6","0.4.0rc1","0.4.0rc2","0.4.0rc3","0.4.0rc4","0.4.0rc5","0.4.0rc6"],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2024/04/GHSA-5jrj-52x8-m64h/GHSA-5jrj-52x8-m64h.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N"}]}