What’s Vulnerable › Vulnerabilities

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

• Severity: medium (CVSS 5.0 v2.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-12-21 · updated 2026-06-17
• Weakness: CWE-670

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.

Affected products

• Crypto Cronos: before 0.6.5 — fixed in 0.6.5
• Crypto Ethermint: before 0.7.3; from 0.8.0 through 0.9.0 — fixed in 0.7.3
• Crypto Evmos: through 0.4.2

How to fix

Upgrade to a fixed version: Crypto Cronos 0.6.5; Crypto Ethermint 0.7.3. Check the vendor advisory for mitigations.

References

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

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