How severe is CVE-2021-39193?

CVE-2021-39193 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability none.

Is CVE-2021-39193 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (64th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-39193?

CVE-2021-39193 affects Parity Frontier. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-39193?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-39193 published?

CVE-2021-39193 was published on 2021-09-03 and last updated on 2026-06-17.

CVE-2021-39193

CVE-2021-39193 is a medium-severity vulnerability in Parity Frontier with a CVSS 3.x base score of 5.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-1284.

Key facts

Severity: Medium (CVSS 3.x base score 5.3)
CVSS v2: 5.0
EPSS exploit prediction: 1% (64th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-1284
Affected product: Parity Frontier
Published: 2021-09-03
Last modified: 2026-06-17

Description

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 is of no effect as it is rejected by the EVM engine. The impact is further limited by Substrate extrinsic size constraints. A patch is available in commit number 0b962f218f0cdd796dadfe26c3f09e68f7861b26. There are no workarounds aside from applying the patch.

Frequently asked questions

What is CVE-2021-39193?: 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 is of no effect as it is rejected by the EVM engine. The impact is further limited by Substrate extrinsic size constraints. A patch is available in commit number 0b962f218f0cdd796dadfe26c3f09e68f7861b26. There are no workarounds aside from applying the patch.
How severe is CVE-2021-39193?: CVE-2021-39193 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability none.
Is CVE-2021-39193 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (64th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-39193?: CVE-2021-39193 affects Parity Frontier. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-39193?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-39193 published?: CVE-2021-39193 was published on 2021-09-03 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:parity:frontier:*:*:*:*:*:*:*:*

More vulnerabilities in Parity Frontier

CVE-2023-45130 — High (CVSS 7.5): Frontier is Substrate's Ethereum compatibility layer. Prior to commit aea528198b3b226e0d20cce878551fd4c0e3d5d0, at the…
CVE-2023-28431 — High (CVSS 7.5): Frontier is an Ethereum compatibility layer for Substrate. Frontier's `modexp` precompile uses `num-bigint` crate under…
CVE-2022-36008 — High (CVSS 7.1): Frontier is Substrate's Ethereum compatibility layer. A security issue was discovered affecting parsing of the RPC…
CVE-2022-21685 — Medium (CVSS 6.5): Frontier is Substrate's Ethereum compatibility layer. Prior to commit number…
CVE-2022-39242 — Medium (CVSS 5.3): Frontier is an Ethereum compatibility layer for Substrate. Prior to commit d3beddc6911a559a3ecc9b3f08e153dbe37a8658,…
CVE-2022-31111 — Medium (CVSS 5.3): Frontier is Substrate's Ethereum compatibility layer. In affected versions the truncation done when converting between…

All CVEs affecting Parity Frontier →

Other CWE-1284 (Improper Validation of Specified Quantity in Input) vulnerabilities

CVE-2026-49777 — Critical (CVSS 10.0): Improper Validation of Specified Quantity in Input vulnerability in ShapedPlugin, LLC Product Slider Pro for…
CVE-2024-8887 — Critical (CVSS 10.0): CIRCUTOR Q-SMT in its firmware version 1.0.4, could be affected by a denial of service (DoS) attack if an attacker with…
CVE-2022-20699 — Critical (CVSS 10.0): Multiple vulnerabilities in Cisco Small Business RV160, RV260, RV340, and RV345 Series Routers could allow an attacker…
CVE-2021-21960 — Critical (CVSS 10.0): A stack-based buffer overflow vulnerability exists in both the LLMNR functionality of Sealevel Systems, Inc. SeaConnect…
CVE-2021-21951 — Critical (CVSS 10.0): An out-of-bounds write vulnerability exists in the CMD_DEVICE_GET_SERVER_LIST_REQUEST functionality of the…
CVE-2021-21950 — Critical (CVSS 10.0): An out-of-bounds write vulnerability exists in the CMD_DEVICE_GET_SERVER_LIST_REQUEST functionality of the…

Browse all CWE-1284 (Improper Validation of Specified Quantity in Input) vulnerabilities →