CVE-2026-44005Public exploitNetwork attack vector

Sandbox escape via host prototype proxy writes

Published May 13, 2026 · Updated May 13, 2026

Prototype pollution in Patrik Simek vm2 3.9.6 through 3.10.5 allows attackers to escape the sandbox via crafted JavaScript. BaseHandler.apply() exposes a host-prototype walking primitive, while BaseHandler.set() and defineProperty() forward sandbox-controlled writes through otherReflectSet() and otherReflectDefineProperty() into shared host prototypes. Default VM and inherited NodeVM configurations are reachable when an application executes attacker-controlled code, permitting modification of host Object, Array, and Function prototypes.

CVSS severity10.0
Critical
EPSS probability0.83%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Prototype pollution in Patrik Simek vm2 3.9.6 through 3.10.5 allows attackers to escape the sandbox via crafted JavaScript. BaseHandler.apply() exposes a host-prototype walking primitive, while BaseHandler.set() and defineProperty() forward sandbox-controlled writes through otherReflectSet() and otherReflectDefineProperty() into shared host prototypes. Default VM and inherited NodeVM configurations are reachable when an application executes attacker-controlled code, permitting modification of host Object, Array, and Function prototypes.

The record

CVE
CVE-2026-44005
Published
May 13, 2026
Updated
May 13, 2026
Vendor
Patrik Simek
Product
vm2
Classifications
CWE-94, CWE-653, CWE-1321, T1211
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 13, 2026CVE publishedPublication date reported by the CVE source.
  2. May 13, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=>= 3.9.6, < 3.11.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Patrik Simek · vm2version=>= 3.9.6, < 3.11.0

Published CVSS scores

10.0GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:H
9.8redhat-SADPCVSS: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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-94Improper Control of Generation of Code ('Code Injection')
CWE-653Improper Isolation or Compartmentalization
CWE-1321Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
T1211Exploitation for Defense Evasion

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo