{"id":"GHSA-5vp3-v4hc-gx76","summary":"UUPSUpgradeable vulnerability in @openzeppelin/contracts","details":"### Impact\n\nUpgradeable contracts using `UUPSUpgradeable` may be vulnerable to an attack affecting uninitialized implementation contracts. We will update this advisory with more information soon.\n\n### Patches\n\nA fix is included in version 4.3.2 of `@openzeppelin/contracts` and `@openzeppelin/contracts-upgradeable`.\n\n### Workarounds\n\nInitialize implementation contracts using `UUPSUpgradeable` by invoking the initializer function (usually called `initialize`). An example is provided [in the forum](https://forum.openzeppelin.com/t/security-advisory-initialize-uups-implementation-contracts/15301).\n\n### References\n\n[Post-mortem](https://forum.openzeppelin.com/t/uupsupgradeable-vulnerability-post-mortem/15680).\n\n### For more information\n\nIf you have any questions or comments about this advisory, or need assistance executing the mitigation, email us at security@openzeppelin.com.","aliases":["CVE-2021-41264"],"modified":"2026-07-08T06:27:43.429315395Z","published":"2021-09-15T20:23:17Z","database_specific":{"github_reviewed_at":"2021-09-14T22:17:42Z","nvd_published_at":"2021-11-12T18:15:00Z","cwe_ids":["CWE-665"],"severity":"CRITICAL","github_reviewed":true},"references":[{"type":"WEB","url":"https://github.com/OpenZeppelin/openzeppelin-contracts/security/advisories/GHSA-5vp3-v4hc-gx76"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2021-41264"},{"type":"WEB","url":"https://github.com/OpenZeppelin/openzeppelin-contracts/commit/024cc50df478d2e8f78539819749e94d6df60592"},{"type":"WEB","url":"https://forum.openzeppelin.com/t/security-advisory-initialize-uups-implementation-contracts/15301"},{"type":"PACKAGE","url":"https://github.com/OpenZeppelin/openzeppelin-contracts"}],"affected":[{"package":{"name":"@openzeppelin/contracts","ecosystem":"npm","purl":"pkg:npm/%40openzeppelin/contracts"},"ranges":[{"type":"SEMVER","events":[{"introduced":"4.1.0"},{"fixed":"4.3.2"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2021/09/GHSA-5vp3-v4hc-gx76/GHSA-5vp3-v4hc-gx76.json"}},{"package":{"name":"@openzeppelin/contracts-upgradeable","ecosystem":"npm","purl":"pkg:npm/%40openzeppelin/contracts-upgradeable"},"ranges":[{"type":"SEMVER","events":[{"introduced":"4.1.0"},{"fixed":"4.3.2"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2021/09/GHSA-5vp3-v4hc-gx76/GHSA-5vp3-v4hc-gx76.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:H/I:H/A:H"}]}