CVE-2022-39242: Incorrect Calculation in Frontier leads to inflated Ethereum chain gas prices

Severity: medium (CVSS 5.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.8% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2022-09-24 · updated 2026-06-17
Weakness: CWE-682

Description

Frontier is an Ethereum compatibility layer for Substrate. Prior to commit d3beddc6911a559a3ecc9b3f08e153dbe37a8658, the worst case weight was always accounted as the block weight for all cases. In case of large EVM gas refunds, this can lead to block spamming attacks -- the adversary can construct blocks with transactions that have large amount of refunds or unused gases with reverts, and as a result inflate up the chain gas prices. The impact of this issue is limited in that the spamming attack would still be costly for any adversary, and it has no ability to alter any chain state. This issue has been patched in commit d3beddc6911a559a3ecc9b3f08e153dbe37a8658. There are no known workarounds.

Affected products

paritytech frontier: before 2022-09-12 — fixed in 2022-09-12

How to fix

Upgrade to a fixed version: paritytech frontier 2022-09-12. Check the vendor advisory for mitigations.

References

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