{"id":"CVE-2020-26242","aliases":["EUVD-2021-1345","GHSA-jm5c-rv3w-w83m","GO-2021-0103"],"status":"published","title":"Denial of service in geth","description":"Go Ethereum, or \"Geth\", is the official Golang implementation of the Ethereum protocol. In Geth before version 1.9.18, there is a Denial-of-service (crash) during block processing. This is fixed in 1.9.18.","severity":{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-12","score":0.0148,"percentile":0.74287,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-125","CWE-191","CWE-400"],"published":"2020-11-25T01:25:15Z","modified":"2026-10-20T10:52:55Z","fixes":[{"ecosystem":"Go","package":"github.com/ethereum/go-ethereum","fixed_in":["1.9.18"],"sources":["ghsa","osv"]},{"ecosystem":"Go","package":"github.com/holiman/uint256","fixed_in":["1.1.1"],"sources":["ghsa","osv"]}],"affected":[{"source":"ghsa","ecosystem":"Go","package":"github.com/ethereum/go-ethereum","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"1.9.16"},{"fixed":"1.9.18"}]}]},{"source":"ghsa","ecosystem":"Go","package":"github.com/holiman/uint256","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0.1.0"},{"fixed":"1.1.1"}]}]},{"source":"osv","ecosystem":"Go","package":"github.com/ethereum/go-ethereum","ranges":[{"type":"SEMVER","events":[{"introduced":"1.9.16"},{"fixed":"1.9.18"}]}]},{"source":"osv","ecosystem":"Go","package":"github.com/holiman/uint256","ranges":[{"type":"SEMVER","events":[{"introduced":"0.1.0"},{"fixed":"1.1.1"}]}]},{"source":"osv","ecosystem":"Go","package":"github.com/holiman/uint256","ranges":[{"type":"SEMVER","events":[{"introduced":"0.1.0"},{"fixed":"1.1.1"}]}]}],"products":[{"vendor":"ethereum","product":"go-ethereum"},{"vendor":"ethereum","product":"go_ethereum"}],"references":[{"url":"https://github.com/ethereum/go-ethereum/security/advisories/GHSA-jm5c-rv3w-w83m","tags":["x_refsource_CONFIRM","x_transferred","Third Party Advisory","advisory","web"]},{"url":"https://blog.ethereum.org/2020/11/12/geth_security_release/","tags":["x_refsource_MISC","x_transferred","Vendor Advisory","advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2020-26242","tags":["advisory"]},{"url":"https://github.com/ethereum/go-ethereum/commit/7163a6664ee664df81b9028ab3ba13b9d65a7196","tags":["web"]},{"url":"https://github.com/holiman/uint256/pull/80","tags":["web","fix"]},{"url":"https://github.com/holiman/uint256/commit/6785da6e3eea403260a5760029e722aa4ff1716d","tags":["web","fix"]},{"url":"https://pkg.go.dev/vuln/GO-2021-0103","tags":["web"]},{"url":"https://blog.ethereum.org/2020/11/12/geth_security_release","tags":["web"]},{"url":"https://github.com/advisories/GHSA-jm5c-rv3w-w83m"},{"url":"https://github.com/ethereum/go-ethereum","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2020-26242","title":"Denial of service in geth","description":"Go Ethereum, or \"Geth\", is the official Golang implementation of the Ethereum protocol. In Geth before version 1.9.18, there is a Denial-of-service (crash) during block processing. This is fixed in 1.9.18.","status":"published","published":"2020-11-25T01:25:15Z","modified":"2024-08-04T15:56:03.57Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","level":"medium","assessor":"cna"}],"updated_at":"2026-11-02T14:35:46.129376Z"}],"euvd":[{"id":"EUVD-2021-1345","description":"Go Ethereum, or \"Geth\", is the official Golang implementation of the Ethereum protocol. In Geth before version 1.9.18, there is a Denial-of-service (crash) during block processing. This is fixed in 1.9.18.","status":"published","published":"2020-11-25T01:25:15Z","modified":"2024-08-04T15:56:03Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"updated_at":"2026-11-03T03:07:15.778249Z"}],"ghsa":[{"id":"GHSA-jm5c-rv3w-w83m","title":"Denial of service in geth","description":"### Impact\nDenial-of-service (crash) during block processing\n\n### Details\n\nAffected versions suffer from a vulnerability which can be exploited through the `MULMOD` operation, by specifying a modulo of `0`: `mulmod(a,b,0)`, causing a `panic` in the underlying library. \nThe crash was in the `uint256` library, where a buffer [underflowed](https://github.com/holiman/uint256/blob/4ce82e695c10ddad57215bdbeafb68b8c5df2c30/uint256.go#L442).\n\n\tif `d == 0`, `dLen` remains `0`\n\nand https://github.com/holiman/uint256/blob/4ce82e695c10ddad57215bdbeafb68b8c5df2c30/uint256.go#L451 will try to access index `[-1]`.\n\nThe `uint256` library was first merged in this [commit](https://github.com/ethereum/go-ethereum/commit/cf6674539c589f80031f3371a71c6a80addbe454), on 2020-06-08. \nExploiting this vulnerabilty would cause all vulnerable nodes to drop off the network. \n\nThe issue was brought to our attention through a [bug report](https://github.com/ethereum/go-ethereum/issues/21367), showing a `panic` occurring on sync from genesis on the Ropsten network.\n \nIt was estimated that the least obvious way to fix this would be to merge the fix into `uint256`, make a new release of that library and then update the geth-dependency.\n\n- https://github.com/holiman/uint256/releases/tag/v1.1.1 was made the same day, \n- PR to address the issue: https://github.com/holiman/uint256/pull/80 \n- PR to update geth deps: https://github.com/ethereum/go-ethereum/pull/21368 \n\n\n\n### Patches\n\nUpgrade to v1.9.18 or higher\n\n### Workarounds\n\nNot at this time\n\n### References\n\nhttps://blog.ethereum.org/2020/11/12/geth_security_release/\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","status":"published","published":"2021-06-29T21:13:20Z","modified":"2025-01-30T14:38:54Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"cwes":["CWE-125","CWE-191","CWE-400"],"updated_at":"2026-11-02T14:38:28.945236Z"}],"nvd":[{"id":"CVE-2020-26242","description":"Go Ethereum, or \"Geth\", is the official Golang implementation of the Ethereum protocol. In Geth before version 1.9.18, there is a Denial-of-service (crash) during block processing. This is fixed in 1.9.18.","status":"published","published":"2020-11-25T02:15:11.127Z","modified":"2026-06-17T03:07:54.18Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","level":"medium","assessor":"secondary"},{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high","assessor":"primary"},{"version":"2.0","score":5,"vector":"AV:N/AC:L/Au:N/C:N/I:N/A:P","level":"medium","assessor":"primary"}],"updated_at":"2026-11-02T14:06:25.394006Z"}],"osv":[{"id":"CVE-2020-26242","description":"Go Ethereum, or \"Geth\", is the official Golang implementation of the Ethereum protocol. In Geth before version 1.9.18, there is a Denial-of-service (crash) during block processing. This is fixed in 1.9.18.","status":"published","published":"2020-11-25T02:15:11.127Z","modified":"2026-10-20T10:52:55.956117425Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"updated_at":"2026-11-02T15:44:15.879068Z"},{"id":"GHSA-jm5c-rv3w-w83m","title":"Denial of service in geth","description":"### Impact\nDenial-of-service (crash) during block processing\n\n### Details\n\nAffected versions suffer from a vulnerability which can be exploited through the `MULMOD` operation, by specifying a modulo of `0`: `mulmod(a,b,0)`, causing a `panic` in the underlying library. \nThe crash was in the `uint256` library, where a buffer [underflowed](https://github.com/holiman/uint256/blob/4ce82e695c10ddad57215bdbeafb68b8c5df2c30/uint256.go#L442).\n\n\tif `d == 0`, `dLen` remains `0`\n\nand https://github.com/holiman/uint256/blob/4ce82e695c10ddad57215bdbeafb68b8c5df2c30/uint256.go#L451 will try to access index `[-1]`.\n\nThe `uint256` library was first merged in this [commit](https://github.com/ethereum/go-ethereum/commit/cf6674539c589f80031f3371a71c6a80addbe454), on 2020-06-08. \nExploiting this vulnerabilty would cause all vulnerable nodes to drop off the network. \n\nThe issue was brought to our attention through a [bug report](https://github.com/ethereum/go-ethereum/issues/21367), showing a `panic` occurring on sync from genesis on the Ropsten network.\n \nIt was estimated that the least obvious way to fix this would be to merge the fix into `uint256`, make a new release of that library and then update the geth-dependency.\n\n- https://github.com/holiman/uint256/releases/tag/v1.1.1 was made the same day, \n- PR to address the issue: https://github.com/holiman/uint256/pull/80 \n- PR to update geth deps: https://github.com/ethereum/go-ethereum/pull/21368 \n\n\n\n### Patches\n\nUpgrade to v1.9.18 or higher\n\n### Workarounds\n\nNot at this time\n\n### References\n\nhttps://blog.ethereum.org/2020/11/12/geth_security_release/\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","status":"published","published":"2021-06-29T21:13:20Z","modified":"2026-07-08T05:59:51.548470893Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"cwes":["CWE-125","CWE-191","CWE-400"],"updated_at":"2026-11-02T15:46:50.687609Z"},{"id":"GO-2021-0103","title":"Denial of service in github.com/holiman/uint256","description":"Due to improper bounds checking, certain mathematical operations can cause a panic via an out of bounds read. If this package is used to process untrusted user inputs, this may be used as a vector for a denial of service attack.","status":"published","published":"2021-07-28T18:08:05Z","modified":"2024-05-20T16:03:47Z","updated_at":"2026-11-02T15:47:00.604718Z"}]}}