{"id":"CVE-2020-26241","aliases":["GHSA-69v6-xc2j-r2jf","GO-2022-0771"],"url":"https://o3.security/vulnerability/CVE-2020-26241","summary":"Shallow copy bug in geth","details":"### Impact\nThis is a Consensus vulnerability, which can be used to cause a chain-split where vulnerable nodes reject the canonical chain. \n\nGeth’s pre-compiled `dataCopy` (at `0x00...04`) contract did a shallow copy on invocation. An attacker could deploy a contract that \n\n- writes `X` to an EVM memory region `R`,\n- calls `0x00..04` with `R` as an argument,\n- overwrites `R` to `Y`,\n- and finally invokes the `RETURNDATACOPY` opcode.\n\nWhen this contract is invoked, a consensus-compliant node would push `X` on the EVM stack, whereas Geth would push `Y`.\n\n\n### Patches\n\nNo standalone patches have been made. \n\n### Workarounds\n\nUpgrade to `1.9.17` or higher.\n\n### References\n\nhttps://blog.ethereum.org/2020/11/12/geth_security_release/\n\n### For more information\nIf you have any questions or comments about this advisory:\n* Open an issue in [go-ethereum](https://github.com/ethereum/go-ethereum)\n* Email us at [security@ethereum.org](mailto:security@ethereum.org)\n","published":"2020-11-25T02:15:11.047Z","modified":"2026-08-07T15:12:15.337192Z","cvss":{"score":7.1,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:L"},"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"Go","name":"github.com/ethereum/go-ethereum","fixedVersion":"1.9.17"}],"fix":{"url":"https://github.com/ethereum/go-ethereum/commit/295693759e5ded05fec0b2fb39359965b60da785","label":"ethereum/go-ethereum@2956937"},"references":[{"type":"ADVISORY","url":"https://blog.ethereum.org/2020/11/12/geth_security_release/"},{"type":"ADVISORY","url":"https://github.com/ethereum/go-ethereum/security/advisories/GHSA-69v6-xc2j-r2jf"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2020-26241"},{"type":"WEB","url":"https://github.com/ethereum/go-ethereum/commit/295693759e5ded05fec0b2fb39359965b60da785"},{"type":"WEB","url":"https://blog.ethereum.org/2020/11/12/geth_security_release"},{"type":"PACKAGE","url":"https://github.com/ethereum/go-ethereum"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-07T15:12:15.337192Z"}}