CVE-2021-25943Network attack vector

Service interruption via unsafe prototype-reaching keypaths

Published May 14, 2021 · Updated Apr 30, 2025

Prototype pollution in 101 1.0.0 through 1.6.3 allows remote attackers to interrupt service via crafted property keypaths. The set function forwards caller-supplied keypaths to keypather.set without rejecting prototype-reaching segments, enabling writes into Object.prototype. Exploitation requires a consuming application to pass attacker-controlled keys into the library; the resulting inherited properties interrupt service or enable code execution through application-specific gadgets.

CVSS severity9.8
Critical
EPSS probability3.30%
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 101 1.0.0 through 1.6.3 allows remote attackers to interrupt service via crafted property keypaths. The set function forwards caller-supplied keypaths to keypather.set without rejecting prototype-reaching segments, enabling writes into Object.prototype. Exploitation requires a consuming application to pass attacker-controlled keys into the library; the resulting inherited properties interrupt service or enable code execution through application-specific gadgets.

The record

CVE
CVE-2021-25943
Published
May 14, 2021
Updated
Apr 30, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-1321
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 14, 2021CVE publishedPublication date reported by the CVE source.
  2. Apr 30, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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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

9.8GitHub Advisory DatabaseCVSS: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.

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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 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.

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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