CVE-2021-23555Public exploitNetwork attack vector

Host code execution via stack-trace Error exposure

Published Feb 11, 2022 · Updated Sep 16, 2024

Sandbox bypass in Patrik Simek vm2 before 3.9.6 allows attackers to execute arbitrary code on the host through a crafted stack trace. Stack-trace generation passes a host Error object into sandbox-controlled setters or getters without isolation, exposing the host prototype chain. Exploitation requires an application to run attacker-controlled JavaScript in vm2; a successful escape grants that code access to the host process.

CVSS severity9.8
Critical
EPSS probability2.88%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Sandbox bypass in Patrik Simek vm2 before 3.9.6 allows attackers to execute arbitrary code on the host through a crafted stack trace. Stack-trace generation passes a host Error object into sandbox-controlled setters or getters without isolation, exposing the host prototype chain. Exploitation requires an application to run attacker-controlled JavaScript in vm2; a successful escape grants that code access to the host process.

The record

CVE
CVE-2021-23555
Published
Feb 11, 2022
Updated
Sep 16, 2024
Vendor
Patrik Simek
Product
vm2
Classifications
CWE-1321
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 11, 2022CVE 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 <3.9.6

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Patrik Simek · vm2version=unspecified <3.9.6

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 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')

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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