CVE-2021-23402Public exploitNetwork attack vector

Object prototype modification via unchecked recursive assignment

Published Jul 2, 2021 · Updated Sep 16, 2024

Prototype pollution in record-like-deep-assign 1.0.1 and earlier allows remote attackers to alter inherited object properties. The deepAssign function recursively assigns untrusted source keys to target properties without rejecting proto, causing crafted input to modify Object.prototype. Exploitation requires a consuming application to pass attacker-controlled objects into the library; polluted properties can alter application behavior or affect its data.

CVSS severity9.8
Critical
EPSS probability1.17%
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 record-like-deep-assign 1.0.1 and earlier allows remote attackers to alter inherited object properties. The deepAssign function recursively assigns untrusted source keys to target properties without rejecting proto, causing crafted input to modify Object.prototype. Exploitation requires a consuming application to pass attacker-controlled objects into the library; polluted properties can alter application behavior or affect its data.

The record

CVE
CVE-2021-23402
Published
Jul 2, 2021
Updated
Sep 16, 2024
Vendor
Kristóf Poduszló
Product
record-like-deep-assign
Classifications
CWE-1321, CWE-915
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 2, 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

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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 <unspecified

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Kristóf Poduszló · record-like-deep-assignversion=0 <unspecified

Published CVSS scores

9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
7.5NIST NVDAV:N/AC:L/Au:N/C:P/I:P/A:P
7.3SnykCVSS:3.1/AV:N/AC:L/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.

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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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-1321Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
CWE-915Improperly Controlled Modification of Dynamically-Determined Object Attributes

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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