CVE-2021-23452Public exploitNetwork attack vector

Prototype pollution via unsafe __proto__ merge

Published Oct 20, 2021 · Updated Sep 16, 2024

Prototype pollution in x-assign 0.1.4 and earlier allows attackers to modify Object.prototype through an untrusted merge source. The assign routine recursively merges an enumerable proto property into the destination without blocking the special key, allowing nested properties to reach the global prototype. Applications must pass attacker-controlled object keys into the library; polluted inherited values can corrupt logic, crash the process, or enable application-specific code execution.

CVSS severity8.6
High
EPSS probability1.55%
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 x-assign 0.1.4 and earlier allows attackers to modify Object.prototype through an untrusted merge source. The assign routine recursively merges an enumerable proto property into the destination without blocking the special key, allowing nested properties to reach the global prototype. Applications must pass attacker-controlled object keys into the library; polluted inherited values can corrupt logic, crash the process, or enable application-specific code execution.

The record

CVE
CVE-2021-23452
Published
Oct 20, 2021
Updated
Sep 16, 2024
Vendor
BinaryOps Software Inc.
Product
x-assign
Classifications
CWE-1321, CWE-915
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 20, 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?

BinaryOps Software Inc. · x-assignversion=0 <unspecified

Published CVSS scores

8.6SnykCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:L
7.5NVDAV:N/AC:L/Au:N/C:P/I:P/A:P
9.8NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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.

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-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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