CVE-2021-39193: Frontier is Substrate's Ethereum compatibility layer

Q: How do I fix CVE-2021-39193?

frontier: upgrade to 2021-09-03. Exact commands for each OS are on this page.

Q: Is CVE-2021-39193 being exploited?

CVE-2021-39193 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2021-39193 affect?

CVE-2021-39193 affects frontier. Severity is medium (CVSS 5.3). Frontier is Substrate's Ethereum compatibility layer. Prior to commit number 0b962f218f0cdd796dadfe26c3f09e68f7861b26, a bug in `pallet-ethereum` can cause invalid transactions to be included in the Ethereum block state in `pallet-ethereum`

Q: How urgent is CVE-2021-39193?

Priority 41/100. Remotely exploitable, no login, no user action

This month

MEDIUM 5.3REMOTEUPGRADE

CVE-2021-39193 is a medium-severity flaw (CVSS 5.3) affecting frontier. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Frontier is Substrate's Ethereum compatibility layer. Prior to commit number 0b962f218f0cdd796dadfe26c3f09e68f7861b26, 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

Why this priority

Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	5.3 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.2% (top 32%)
CISA exploited list	No
Weakness	CWE-20, CWE-1284
Published	2021-09-03
Last modified	2026-06-17

Publisher (CNA): GitHub, Inc. · Vendor: parity

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2021-09-03 18:15 UTCPublished CVE record published
2026-06-17 04:03 UTCUpdated Record last modified

parity frontier UPGRADE

Affected: < 2021-09-03

Fixed in: 2021-09-03

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy frontier || rpm -q frontier || frontier --version

2. UPGRADE to 2021-09-03 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade frontier

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade frontier

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2021-39193?

frontier: upgrade to 2021-09-03. Exact commands for each OS are on this page.

Is CVE-2021-39193 being exploited?

CVE-2021-39193 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2021-39193 affect?

CVE-2021-39193 affects frontier. Severity is medium (CVSS 5.3). Frontier is Substrate's Ethereum compatibility layer. Prior to commit number 0b962f218f0cdd796dadfe26c3f09e68f7861b26, a bug in `pallet-ethereum` can cause invalid transactions to be included in the Ethereum block state in `pallet-ethereum`

How urgent is CVE-2021-39193?

Priority 41/100. Remotely exploitable, no login, no user action

Related CVEs

CVE-2023-45130 HIGH 7.5 UPGRADE Frontier is Substrate's Ethereum compatibility layer
CVE-2023-28431 HIGH 7.5 UPGRADE Frontier is an Ethereum compatibility layer for Substrate
CVE-2022-39242 MEDIUM 5.3 UPGRADE Frontier is an Ethereum compatibility layer for Substrate
CVE-2022-36008 HIGH 7.1 MITIGATE Frontier is Substrate's Ethereum compatibility layer
CVE-2022-31111 MEDIUM 5.3 MITIGATE Frontier is Substrate's Ethereum compatibility layer

References

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