CVE-2021-21413

Sandbox escape via Reference prototype-chain traversal

Published Mar 30, 2021 · Updated Aug 3, 2024

Sandbox escape in Marcel Laverdet isolated-vm before 4.0.0 allows attackers to access the host Node.js isolate via exposed References. The Reference get family follows the underlying object's prototype chain, letting untrusted isolate code acquire the host Function object; NativeModule access can then load native code. Exploitation requires an application to expose a Reference to attacker-controlled isolate code, and arbitrary native-code execution additionally depends on a usable file-upload path.

CVSS severity8.0
High
EPSS probability0.71%
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 Marcel Laverdet isolated-vm before 4.0.0 allows attackers to access the host Node.js isolate via exposed References. The Reference get family follows the underlying object's prototype chain, letting untrusted isolate code acquire the host Function object; NativeModule access can then load native code. Exploitation requires an application to expose a Reference to attacker-controlled isolate code, and arbitrary native-code execution additionally depends on a usable file-upload path.

The record

CVE
CVE-2021-21413
Published
Mar 30, 2021
Updated
Aug 3, 2024
Vendor
Marcel Laverdet
Product
isolated-vm
Classifications
CWE-913, T1059.007
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 30, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 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=< 4.0.0

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

Marcel Laverdet · isolated-vmversion=< 4.0.0

Published CVSS scores

5.8NIST NVDAV:A/AC:L/Au:N/C:P/I:P/A:P
8.0GitHub CNACVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N
9.6NIST NVDCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/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)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-913Improper Control of Dynamically-Managed Code Resources
T1059.007JavaScript

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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