CVE-2020-26241

Shallow copy bug in geth

HIGH
7.1
CVSS Score
Published: November 25, 2020 at 01:25 AM UTC
Updated: June 17, 2026 at 03:07 AM UTC
1 product affected across 1 vendorGo Ethereum

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Severity
HIGH7.1
Exploit prediction
EPSS 1%

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 1.9.17
Affected range stops below 1.9.17, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

CVSS

Attack Vector
NETWORK
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
HIGH
Availability
LOW
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-682

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