CVE-2022-39242 is a medium-severity (CVSS 5.3) CWE-682 vulnerability in pallet-ethereum. No vendor fix is recorded yet; mitigation options are listed below.
Weight not properly refunded after EVM execution
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2022-39242.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2022-39242 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 378,156 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
pallet-ethereumReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects crates.io packages — download data is not available via public APIs for these ecosystems.
Description
Impact
Previously, 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. This issue is fixed by properly refund unused weights after each EVM execution.
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.
Patches
The issue is fixed in https://github.com/paritytech/frontier/pull/851
Workarounds
None.
References
Are there any links users can visit to find out more?
For more information
If you have any questions or comments about this advisory:
- Open an issue in Frontier repo
- Email Wei
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | pallet-ethereum | all versions | No fix |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for pallet-ethereum, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Remediation status
No patched version of pallet-ethereum has shipped for CVE-2022-39242 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.
Mitigate without a patch
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2022-39242 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2022-39242. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2022-39242 in your dependencies?
O3 Security finds CVE-2022-39242 across crates.io dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.