CVE-2024-21505Network attack vector

Service interruption via insecure recursive prototype merge

Published Mar 25, 2024 · Updated Aug 23, 2024

Prototype pollution in ChainSafe Systems web3-utils before 4.2.1 allows attackers to alter inherited object behavior via crafted input. The format and mergeDeep utilities pass crafted nested properties through an insecure recursive merge that can reach and modify an object's prototype. Exploitation requires an application to pass attacker-controlled objects to either utility, and polluted values can change later property lookups or interrupt the process.

CVSS severity7.5
High
EPSS probability0.71%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Prototype pollution in ChainSafe Systems web3-utils before 4.2.1 allows attackers to alter inherited object behavior via crafted input. The format and mergeDeep utilities pass crafted nested properties through an insecure recursive merge that can reach and modify an object's prototype. Exploitation requires an application to pass attacker-controlled objects to either utility, and polluted values can change later property lookups or interrupt the process.

The record

CVE
CVE-2024-21505
Published
Mar 25, 2024
Updated
Aug 23, 2024
Vendor
ChainSafe Systems
Product
web3-utils
Classifications
CWE-1321
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 25, 2024CVE publishedPublication date reported by the CVE source.
  2. Aug 23, 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <4.2.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

ChainSafe Systems · web3-utilsversion=0 <4.2.1

Published CVSS scores

7.5GitHub Advisory DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-1321Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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