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MEDIUM severity

CVE-2021-39193 — pallet-ethereum

MEDIUMFix: paritytech/frontier@0b962f2

CVE-2021-39193 is a medium-severity (CVSS 5.3) Improper Input Validation vulnerability in pallet-ethereum. No vendor fix is recorded yet; mitigation options are listed below.

Transaction validity oversight in pallet-ethereum

Also known asGHSA-hw4v-5x4h-c3xm
Published
Updated
Affected
1 pkg
Patched
See advisory
Exploits
None indexed
Exploitation data as of Oct 9, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
1.2%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs67th percentile — riskier than 67% of all scored CVEsHighest risk
0.00%0.56%1.13%1.69%0.4%1.2%Apr 26Aug 26Oct 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2021-39193 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 385,386 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected
🦀pallet-ethereum

Real-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

A bug in pallet-ethereum can cause invalid transactions to be included in the Ethereum block state in pallet-ethereum due to not validating the input data size. Any invalid transactions included this way have no possibility to alter the internal Ethereum or Substrate state. The transaction will appear to have be included, but is of no effect as it is rejected by the EVM engine. The impact is further limited by Substrate extrinsic size constraints.

Patches

Patches are applied in PR #465.

Workarounds

None.

References

Patch PR: https://github.com/paritytech/frontier/pull/465

For more information

If you have any questions or comments about this advisory:

Affected Packages

1 total
EcosystemPackageVulnerable rangeFix
🦀crates.iopallet-ethereumall versionsNo fix

Affected Products

1 product · 1 configurations
Application
frontierparity
< 2021-09-03
range

Detection & mitigation playbook

Open-source dependency

  1. Detect

    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.

  2. Remediation status

    No patched version of pallet-ethereum has shipped for CVE-2021-39193 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.

  3. Mitigate without a patch

    Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Frequently Asked Questions

### Impact A bug in `pallet-ethereum` can cause invalid transactions to be included in the Ethereum block state in `pallet-ethereum` due to not validating the input data size. Any invalid transactions included this way have no possibility to alter the internal Ethereum or Substrate state. The transaction will appear to have be included, but is of no effect as it is rejected by the EVM engine. The impact is further limited by Substrate extrinsic size constraints. ### Patches Patches are applied in PR #465. ### Workarounds None. ### References Patch PR: https://github.com/paritytech/front
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CVE-2021-39193: pallet-ethereum (Medium 5.3)