CVE-2021-23413Network attack vector

Denial of service via prototype-key ZIP filenames

Published Jul 25, 2021 · Updated Sep 16, 2024

Prototype pollution in JSZip before 2.7.0 and 3.0.0 through 3.6.0 allows attackers to disrupt applications via crafted ZIP names. The JSZip constructor stores files in a normal object, allowing names such as proto and toString to replace inherited attributes in the returned files map. Exploitation requires a consuming application to accept attacker-controlled ZIP names; published material does not identify a specific crash or hang.

CVSS severity5.3
Medium
EPSS probability3.44%
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 JSZip before 2.7.0 and 3.0.0 through 3.6.0 allows attackers to disrupt applications via crafted ZIP names. The JSZip constructor stores files in a normal object, allowing names such as proto and toString to replace inherited attributes in the returned files map. Exploitation requires a consuming application to accept attacker-controlled ZIP names; published material does not identify a specific crash or hang.

The record

CVE
CVE-2021-23413
Published
Jul 25, 2021
Updated
Sep 16, 2024
Vendor
JSZip Project
Product
JSZip
Classifications
CWE-1321
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 25, 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=unspecified <3.7.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

JSZip Project · JSZipversion=unspecified <3.7.0

Published CVSS scores

5.3GitHub Advisory DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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 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.

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Technologies

Your stack

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Your stack

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