---
id: CVE-2021-43839
aliases:
  - GHSA-f854-hpxv-cw9r
title: Drainage of FeeCollector's Block Transaction Fees in cronos
summary: Drainage of FeeCollector's Block Transaction Fees in cronos
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N'
vendor: crypto-org-chain
product: github.com/crypto-org-chain/cronos
ecosystem: go
affected:
  - github.com/crypto-org-chain/cronos < 0.6.5
  - 'github.com/tharsis/ethermint >= 0.8.0, < 0.10.0'
  - github.com/tharsis/evmos <= 0.4.2
  - github.com/tharsis/ethermint < 0.7.3
patched:
  - github.com/crypto-org-chain/cronos 0.6.5
  - github.com/tharsis/ethermint 0.10.0
  - github.com/tharsis/ethermint 0.7.3
published: '2022-01-06'
updated: '2026-07-08'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/GHSA-f854-hpxv-cw9r'
references:
  - url: >-
      https://github.com/crypto-org-chain/cronos/security/advisories/GHSA-f854-hpxv-cw9r
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2021-43839'
  - url: 'https://github.com/crypto-org-chain/cronos/pull/270'
  - url: >-
      https://github.com/crypto-org-chain/cronos/commit/150ef237b37ac28c8136e1c0f494932860b9ebe8
  - url: 'https://github.com/crypto-org-chain/cronos'
tags:
  - osv
  - go
epss: 0.01313
epssPercentile: 0.69491
ingestedAt: '2026-07-09T18:56:36.337Z'
---

## Overview

### Impact
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.

User funds and balances are safe.


### Patches
This problem has been patched in Cronos v0.6.5 on the mempool level.
The next network upgrade with consensus-breaking changes will patch it on the consensus level.

### Workarounds
There are no tested workarounds. All validator node operators are recommended to upgrade to Cronos v0.6.5 at their earliest possible convenience.

### Credits
Thank you to @zb3 for reporting this issue on [Cronos Immunefi Bug Bounty Program](https://immunefi.com/bounty/cronos/), to @cyril-crypto for reproducing the issue and to @yihuang and @thomas-nguy for patching the issue on the CheckTx (mempool) and the DeliverTx (consensus) levels.

### For more information
If you have any questions or comments about this advisory:
* Open a discussion in [crypto-org-chain/cronos](https://github.com/crypto-org-chain/cronos/discussions/new)
* Email us at [chain@crypto.org](mailto:chain@crypto.org)


## Affected packages

- `github.com/crypto-org-chain/cronos < 0.6.5`
- `github.com/tharsis/ethermint >= 0.8.0, < 0.10.0`
- `github.com/tharsis/evmos <= 0.4.2`
- `github.com/tharsis/ethermint < 0.7.3`

## Remediation

Upgrade to a patched release:

- `github.com/crypto-org-chain/cronos 0.6.5`
- `github.com/tharsis/ethermint 0.10.0`
- `github.com/tharsis/ethermint 0.7.3`