CVE-2018-20421
CVSS v3
7.5
HIGH
EPSS Score
1.5 %
exploit probability, as of 2026-09-25
CISA KEV
No
known exploited
Exploitation
—
SSVC status
Description
Go Ethereum (aka geth) 1.8.19 allows attackers to cause a denial of service (memory consumption) by rewriting the length of a dynamic array in memory, and then writing data to a single memory location with a large index number, as demonstrated by use of "assembly { mstore }" followed by a "c[0xC800000] = 0xFF" assignment.
Technical details
- Published
- 2018-12-24
Frequently asked questions
What is CVE-2018-20421?
Go Ethereum (aka geth) 1.8.19 allows attackers to cause a denial of service (memory consumption) by rewriting the length of a dynamic array in memory, and then writing data to a single memory location with a large index number, as demonstrated by use of "assembly { mstore }" followed by a "c[0xC800000] = 0xFF" assignment.
Is CVE-2018-20421 actively exploited?
Active exploitation of CVE-2018-20421 has not been confirmed. Its EPSS score was 1.5% on 2026-09-25, the estimated probability of exploitation in the next 30 days.
What is the CVSS score for CVE-2018-20421?
CVE-2018-20421 has a CVSS v3 base score of 7.5 (HIGH severity).
Is CVE-2018-20421 affecting your environment?
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