CVE-2020-26800Public exploit

Client crash via deeply nested JSON configuration

Published Jan 11, 2021 · Updated Aug 4, 2024

Stack overflow in the Aleth Ethereum C++ client 1.8.0 and earlier allows attackers to crash the client via a crafted config.json file. The configuration parser accepts at least 3,764 unmatched opening square brackets and exhausts the process stack, terminating Aleth with a segmentation fault. Exploitation requires Aleth to be started with the malicious file through the --config option; the demonstrated consequence is a client crash.

CVSS severity5.5
Medium
EPSS probability1.20%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stack overflow in the Aleth Ethereum C++ client 1.8.0 and earlier allows attackers to crash the client via a crafted config.json file. The configuration parser accepts at least 3,764 unmatched opening square brackets and exhausts the process stack, terminating Aleth with a segmentation fault. Exploitation requires Aleth to be started with the malicious file through the --config option; the demonstrated consequence is a client crash.

The record

CVE
CVE-2020-26800
Published
Jan 11, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-787, T1204.002
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 11, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
4.3NIST NVDAV:N/AC:M/Au:N/C:N/I:N/A:P

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-787Out-of-bounds Write
T1204.002Malicious File

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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