CVE-2021-23449Public exploitNetwork attack vector

Host code execution via dynamic-import prototype pollution

Published Oct 18, 2021 · Updated Sep 17, 2024

Prototype pollution in Patrik Simek's vm2 before 3.9.4 allows remote attackers to escape the sandbox and execute host code. A rejected dynamic import returns a promise whose exposed prototype chain lets sandboxed JavaScript modify the host Object prototype and reach Function. Exploitation requires an application to pass attacker-controlled JavaScript into vm2; escape grants the privileges of the host Node.js process.

CVSS severity9.8
Critical
EPSS probability3.59%
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 Patrik Simek's vm2 before 3.9.4 allows remote attackers to escape the sandbox and execute host code. A rejected dynamic import returns a promise whose exposed prototype chain lets sandboxed JavaScript modify the host Object prototype and reach Function. Exploitation requires an application to pass attacker-controlled JavaScript into vm2; escape grants the privileges of the host Node.js process.

The record

CVE
CVE-2021-23449
Published
Oct 18, 2021
Updated
Sep 17, 2024
Vendor
Patrik Simek
Product
vm2
Classifications
CWE-915, CWE-1321, T1059.007
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 18, 2021CVE 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=unspecified <3.9.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Patrik Simek · vm2version=unspecified <3.9.4

Published CVSS scores

9.8SnykCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
10.0NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
7.5NIST NVDAV:N/AC:L/Au:N/C:P/I:P/A: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.

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-915Improperly Controlled Modification of Dynamically-Determined Object Attributes
CWE-1321Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
T1059.007JavaScript/JScript

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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