CVE-2021-23702Public exploitNetwork attack vector

Property injection via unsafe recursive merge

Published Feb 18, 2022 · Updated Sep 17, 2024

Prototype pollution in object-extend 0.5.0 and earlier allows remote authenticated users to inject inherited properties via crafted merge input. The recursive merge routine follows an attacker-controlled proto property and copies its nested properties onto Object.prototype. Exploitation requires a consuming application to pass attacker-controlled objects to the library; the demonstrated result is process-wide property injection, while further effects depend on application gadgets.

CVSS severity7.6
High
EPSS probability1.38%
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 object-extend 0.5.0 and earlier allows remote authenticated users to inject inherited properties via crafted merge input. The recursive merge routine follows an attacker-controlled proto property and copies its nested properties onto Object.prototype. Exploitation requires a consuming application to pass attacker-controlled objects to the library; the demonstrated result is process-wide property injection, while further effects depend on application gadgets.

The record

CVE
CVE-2021-23702
Published
Feb 18, 2022
Updated
Sep 17, 2024
Vendor
Bernhard Wanger
Product
object-extend
Classifications
CWE-1321
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 18, 2022CVE publishedPublication date reported by the CVE source.
  2. Sep 17, 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?

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  1. Affected versionversion=0.0.0 <unspecified

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Bernhard Wanger · object-extendversion=0.0.0 <unspecified

Published CVSS scores

7.6SnykCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:L
9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
7.2SnykCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:L/E: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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

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

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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