How severe is CVE-2020-26241?

CVE-2020-26241 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.

Is CVE-2020-26241 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (61st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-26241?

CVE-2020-26241 affects Ethereum Go Ethereum. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2020-26241?

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

When was CVE-2020-26241 published?

CVE-2020-26241 was published on 2020-11-25 and last updated on 2026-06-17.

CVE-2020-26241

CVE-2020-26241 is a medium-severity vulnerability in Ethereum Go Ethereum with a CVSS 3.x base score of 6.5. 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-682.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
CVSS v2: 5.5
EPSS exploit prediction: 1% (61st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-682
Affected product: Ethereum Go Ethereum
Published: 2020-11-25
Last modified: 2026-06-17

Description

Go Ethereum, or "Geth", is the official Golang implementation of the Ethereum protocol. This is a Consensus vulnerability in Geth before version 1.9.17 which can be used to cause a chain-split where vulnerable nodes reject the canonical chain. Geth's pre-compiled dataCopy (at 0x00...04) contract did a shallow copy on invocation. An attacker could deploy a contract that writes X to an EVM memory region R, then calls 0x00..04 with R as an argument, then overwrites R to Y, and finally invokes the RETURNDATACOPY opcode. When this contract is invoked, a consensus-compliant node would push X on the EVM stack, whereas Geth would push Y. This is fixed in version 1.9.17.

Frequently asked questions

What is CVE-2020-26241?: Go Ethereum, or "Geth", is the official Golang implementation of the Ethereum protocol. This is a Consensus vulnerability in Geth before version 1.9.17 which can be used to cause a chain-split where vulnerable nodes reject the canonical chain. Geth's pre-compiled dataCopy (at 0x00...04) contract did a shallow copy on invocation. An attacker could deploy a contract that writes X to an EVM memory region R, then calls 0x00..04 with R as an argument, then overwrites R to Y, and finally invokes the RETURNDATACOPY opcode. When this contract is invoked, a consensus-compliant node would push X on the EVM stack, whereas Geth would push Y. This is fixed in version 1.9.17.
How severe is CVE-2020-26241?: CVE-2020-26241 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.
Is CVE-2020-26241 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (61st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-26241?: CVE-2020-26241 affects Ethereum Go Ethereum. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2020-26241?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2020-26241 published?: CVE-2020-26241 was published on 2020-11-25 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:ethereum:go_ethereum:*:*:*:*:*:*:*:*

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