CVE-2021-23438Public exploitNetwork attack vector

Prototype pollution via array path type confusion

Published Sep 1, 2021 · Updated Sep 16, 2024

Type confusion in mpath before 0.8.4 allows remote attackers to pollute object prototypes through a crafted path array. In set() and unset(), an array-valued segment makes ignoreProperties.indexOf() use array comparison, allowing ['proto'] to evade the string denylist. The gate is an application passing attacker-controlled array segments into mpath, after which inherited-property writes can alter application behavior.

CVSS severity5.6
Medium
EPSS probability1.72%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Type confusion in mpath before 0.8.4 allows remote attackers to pollute object prototypes through a crafted path array. In set() and unset(), an array-valued segment makes ignoreProperties.indexOf() use array comparison, allowing ['proto'] to evade the string denylist. The gate is an application passing attacker-controlled array segments into mpath, after which inherited-property writes can alter application behavior.

The record

CVE
CVE-2021-23438
Published
Sep 1, 2021
Updated
Sep 16, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-1321, CWE-843, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 1, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 16, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.5NIST NVDAV:N/AC:L/Au:N/C:P/I:P/A:P
9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
5.6SnykCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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 exploitPublished

Weakness, pattern, technique

CWE-1321Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
CWE-843Access of Resource Using Incompatible Type ('Type Confusion')
T1190Exploit Public-Facing Application

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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