CVE-2023-37903Public exploitNetwork attack vector

Host code execution via custom inspect callback

Published Jul 21, 2023 · Updated Nov 3, 2025

Sandbox escape in Patrik Simek vm2 before 3.10.3 allows attackers to execute arbitrary host code through a custom inspect callback. A cross-realm Symbol.for key installs a Node.js custom inspect callback; WebAssembly.compileStreaming triggers host-side inspection and leaks the host inspect function into sandbox code. The attacker must already control JavaScript executed inside a vm2 sandbox; successful escape runs code with the host Node.js process's privileges.

CVSS severity9.8
Critical
EPSS probability4.21%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Sandbox escape in Patrik Simek vm2 before 3.10.3 allows attackers to execute arbitrary host code through a custom inspect callback. A cross-realm Symbol.for key installs a Node.js custom inspect callback; WebAssembly.compileStreaming triggers host-side inspection and leaks the host inspect function into sandbox code. The attacker must already control JavaScript executed inside a vm2 sandbox; successful escape runs code with the host Node.js process's privileges.

The record

CVE
CVE-2023-37903
Published
Jul 21, 2023
Updated
Nov 3, 2025
Vendor
Patrik Simek
Product
vm2
Classifications
CWE-78, T1059.007
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 21, 2023CVE publishedPublication date reported by the CVE source.
  2. Nov 3, 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?

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

  1. Affected versionversion=<= 3.9.19

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Patrik Simek · vm2version=<= 3.9.19

Published CVSS scores

10.0NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
9.8GitHub, Inc.CVSS: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-78Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
T1059.007Command and Scripting Interpreter: JavaScript/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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