{"id":"CVE-2021-21369","url":"https://www.cyber-defence.io/tools/cve/CVE-2021-21369","generatedAt":"2026-10-27T22:32:24.549Z","title":"In Besu before version 1.5.1 there is a denial-of-service vulnerability involving the HTTP JSON-RPC API service.","description":"Hyperledger Besu is an open-source, MainNet compatible, Ethereum client written in Java. In Besu before version 1.5.1 there is a denial-of-service vulnerability involving the HTTP JSON-RPC API service. If username and password authentication is enabled for the HTTP JSON-RPC API service, then prior to making any requests to an API endpoint the requestor must use the login endpoint to obtain a JSON web token (JWT) using their credentials. A single user can readily overload the login endpoint with invalid requests (incorrect password). As the supplied password is checked for validity on the main vertx event loop and takes a relatively long time this can cause the processing of other valid requests to fail. A valid username is required for this vulnerability to be exposed. This has been fixed in version 1.5.1.","published":"2021-03-09T18:15:18.000Z","lastModified":"2026-06-17T03:35:24.000Z","status":"Modified","sourceIdentifier":"security-advisories@github.com","cvss":{"version":"3.1","score":6.5,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"},"cwe":["CWE-400"],"affected":["linuxfoundation/besu"],"epss":{"score":0.01668,"percentile":0.76604,"date":"2026-10-26","history":[]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"low","text":"Lower severity and a low EPSS score (1.67%). Track it; it rarely justifies an emergency change on its own."},"changes":[],"references":[{"url":"https://github.com/hyperledger/besu/blob/master/CHANGELOG.md#151","tags":["Release Notes","Third Party Advisory"],"source":"security-advisories@github.com"},{"url":"https://github.com/hyperledger/besu/commit/06e35a58c07a30c0fbdc0aae45a3e8b06b53c022","tags":["Patch","Third Party Advisory"],"source":"security-advisories@github.com"},{"url":"https://github.com/hyperledger/besu/pull/1144","tags":["Patch","Third Party Advisory"],"source":"security-advisories@github.com"},{"url":"https://github.com/hyperledger/besu/security/advisories/GHSA-qgfj-mjpc-7w3q","tags":["Third Party Advisory"],"source":"security-advisories@github.com"},{"url":"https://github.com/hyperledger/besu/blob/master/CHANGELOG.md#151","tags":["Release Notes","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://github.com/hyperledger/besu/commit/06e35a58c07a30c0fbdc0aae45a3e8b06b53c022","tags":["Patch","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://github.com/hyperledger/besu/pull/1144","tags":["Patch","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://github.com/hyperledger/besu/security/advisories/GHSA-qgfj-mjpc-7w3q","tags":["Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2021-21369","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}