{"id":"CVE-2023-30837","aliases":["GHSA-mgv8-gggw-mrg6","PYSEC-2023-76"],"title":"vyper vulnerable to storage allocator overflow","summary":"vyper vulnerable to storage allocator overflow","severity":"high","cvss":7.5,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","vendor":"vyper","product":"vyper","ecosystem":"pip","affected":["vyper < 0.3.8"],"patched":["vyper 0.3.8"],"published":"2023-05-05","updated":"2026-09-10","sourceUpdated":"2026-09-10T03:50:01.648781390Z","source":"OSV","sourceUrl":"https://osv.dev/vulnerability/GHSA-mgv8-gggw-mrg6","references":[{"url":"https://github.com/vyperlang/vyper/security/advisories/GHSA-mgv8-gggw-mrg6"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2023-30837"},{"url":"https://github.com/vyperlang/vyper/commit/0bb7203b584e771b23536ba065a6efda457161bb"},{"url":"https://github.com/pypa/advisory-database/tree/main/vulns/vyper/PYSEC-2023-76.yaml"},{"url":"https://github.com/vyperlang/vyper"}],"tags":["osv","pip"],"epss":0.00697,"epssPercentile":0.51632,"ingestedAt":"2026-09-12T03:13:01.711Z","slug":"CVE-2023-30837","body":"## Overview\n\n### Impact\nThe storage allocator does not guard against allocation overflows. This can result in vulnerabilities like the following:\n```vyper\nowner: public(address)\ntake_up_some_space: public(uint256[10])\nbuffer: public(uint256[max_value(uint256)])\n\n@external\ndef initialize():\n    self.owner = msg.sender\n\n@external\ndef foo(idx: uint256, data: uint256):\n    self.buffer[idx] = data\n```\nPer @toonvanhove, \"An attacker can overwrite the owner variable by calling this contract with calldata: `0x04bc52f8 fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff5 ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff` (spaces inserted for readability)\n`0x04bc52f8` is the selector for `foo(uint256, uint256)`, and the last argument `fff...fff` is the new value for the owner variable.\"\n\n### Patches\npatched in 0bb7203b584e771b23536ba065a6efda457161bb\n\n### Workarounds\n_Is there a way for users to fix or remediate the vulnerability without upgrading?_\n\n### References\n_Are there any links users can visit to find out more?_\n\n\n## Affected packages\n\n- `vyper < 0.3.8`\n\n## Remediation\n\nUpgrade to a patched release:\n\n- `vyper 0.3.8`","depth":"twilight","depthScore":41,"depthScoreParts":{"impact":41.3,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}