{"id":"CVE-2023-23940","aliases":["GHSA-626q-v9j4-mcp4","PYSEC-2023-39"],"url":"https://o3.security/vulnerability/CVE-2023-23940","summary":"OpenZeppelin Contracts for Cairo is vulnerable to signature validation bypass","details":"### Cause\n`is_valid_eth_signature` is missing a call to `finalize_keccak` after calling `verify_eth_signature`. \n\n### Impact\nAs a result, any contract using `is_valid_eth_signature` from the account library (such as the `EthAccount` preset) is vulnerable to a malicious sequencer. Specifically, the malicious sequencer would be able to bypass signature validation to impersonate an instance of these accounts.\n\n### Risk\nIn order to exploit this vulnerability, it is required to control a sequencer or prover since they're the ones executing the hints, being able to inject incorrect keccak results.\n\nToday StarkWare is the only party running both a prover or a sequencer, greatly reducing the risk of exploit.\n\n### Patches\nThe issue has been patched in 0.6.1.\n\n### For more information\nIf you have any questions or comments about this advisory:\n* Open an issue in [the Contracts for Cairo repository](https://github.com/OpenZeppelin/cairo-contracts/issues/new/choose)\n* Email us at [security@openzeppelin.com](mailto:security@openzeppelin.com)","published":"2023-02-03T19:43:11.178Z","modified":"2026-08-12T03:51:16.564323570Z","cvss":{"score":6.4,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:H/A:L"},"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"PyPI","name":"openzeppelin-cairo-contracts","fixedVersion":"0.6.1"}],"fix":{"url":"https://github.com/OpenZeppelin/cairo-contracts/pull/542/commits/6d4cb750478fca2fd916f73297632f899aca9299","label":"OpenZeppelin/cairo-contracts#542"},"references":[{"type":"WEB","url":"https://github.com/OpenZeppelin/cairo-contracts/pull/542/commits/6d4cb750478fca2fd916f73297632f899aca9299"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/23xxx/CVE-2023-23940.json"},{"type":"ADVISORY","url":"https://github.com/OpenZeppelin/cairo-contracts/security/advisories/GHSA-626q-v9j4-mcp4"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2023-23940"},{"type":"PACKAGE","url":"https://github.com/OpenZeppelin/cairo-contracts"},{"type":"WEB","url":"https://github.com/pypa/advisory-database/tree/main/vulns/openzeppelin-cairo-contracts/PYSEC-2023-39.yaml"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:16.564323570Z"}}