CVE-2020-26241

moderate-risk
Published 2020-11-25

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.

Do I need to act?

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0.30% chance of exploitation
EPSS score — low exploit probability
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Not on CISA KEV list
No confirmed active exploitation reported to CISA
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Patch status unknown
Check vendor advisories for fix availability and mitigation guidance
6
CVSS 6.5/10 Medium
NETWORK / LOW complexity

Affected Products (1)

Affected Vendors

Ethereum

References (4)

Vendor Advisory https://blog.ethereum.org/2020/11/12/geth_security_release/
Third Party Advisory https://github.com/ethereum/go-ethereum/security/advisories/GHSA-69v6-xc2j-r2jf
Vendor Advisory https://blog.ethereum.org/2020/11/12/geth_security_release/
Third Party Advisory https://github.com/ethereum/go-ethereum/security/advisories/GHSA-69v6-xc2j-r2jf
30
/ 100
moderate-risk
Severity 24/34 · High
Exploitability 1/34 · Minimal
Exposure 5/34 · Minimal