# [CRIT] [GHSA / CRITICAL] CVE-2026-47131: vm2 has a Sandbox Escape issue

**Source:** GitHub Security Advisories
**Published:** 2026-05-29
**Article:** https://github.com/advisories/GHSA-v6mx-mf47-r5wg

## Threat Profile

vm2 has a Sandbox Escape issue

### Summary
By combining `Buffer.call.call({}.__lookupGetter__, Buffer, "__proto__")`, `Buffer.call.call({}.__lookupSetter__, Buffer, "__proto__")`, and Node.js's `ERR_INVALID_ARG_TYPE` Error, the host's `TypeError` constructor can be obtained, which allows the escape from the sandbox.
This allows attackers to run arbitrary code.

### PoC
```js
"use strict";

const { VM } = require("vm2");
const vm = new VM();

vm.run(`
  "use strict";

  const getProto = Buffer.c…

## Indicators of Compromise (high-fidelity only)

- **CVE:** `CVE-2026-47131`

## MITRE ATT&CK Techniques

- **T1190** — Exploit Public-Facing Application
- **T1204.002** — User Execution: Malicious File
- **T1059.007** — Command and Scripting Interpreter: JavaScript
- **T1059** — Command and Scripting Interpreter
- **T1068** — Exploitation for Privilege Escalation

## Kill chain phases observed

_(none detected from narrative keywords)_

## Recommended hunts

### vm2 sandbox-escape PoC strings observed in inbound HTTP request body / WAF

`UC_177_2` · phase: **exploit** · confidence: **High** · AI-generated for this article

**Splunk SPL (CIM):**
```spl
| tstats `summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Web.Web where (Web.url="*__lookupGetter__*" OR Web.url="*__lookupSetter__*" OR Web.url="*compileStreaming*" OR Web.url="*Buffer.call.call*" OR Web.url="*mainModule.require*" OR Web.http_user_agent="*constructor.constructor*") by Web.src Web.dest Web.url Web.http_method Web.status | `drop_dm_object_name(Web)` | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`
```

**Defender KQL:**
```kql
// Defender has no inbound HTTP-body table; pivot via DeviceNetworkEvents to Node processes that received the payload then look at child shells
DeviceProcessEvents
| where Timestamp > ago(7d)
| where InitiatingProcessFileName =~ "node.exe"
| where FileName in~ ("cmd.exe","powershell.exe","pwsh.exe","bash.exe","sh.exe","wmic.exe","mshta.exe")
| where ProcessCommandLine has_any ("echo pwned","child_process","execSync")
| project Timestamp, DeviceName, AccountName, InitiatingProcessCommandLine, FileName, ProcessCommandLine, InitiatingProcessParentFileName
| order by Timestamp desc
```

### Node.exe spawning OS shell after vm2 sandbox exploitation

`UC_177_3` · phase: **install** · confidence: **High** · AI-generated for this article

**Splunk SPL (CIM):**
```spl
| tstats `summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where Processes.parent_process_name="node.exe" Processes.process_name IN ("cmd.exe","powershell.exe","pwsh.exe","bash.exe","sh.exe","wmic.exe","mshta.exe") (Processes.process="*echo pwned*" OR Processes.process="*child_process*" OR Processes.process="*execSync*" OR Processes.process="*mainModule.require*") by Processes.dest Processes.user Processes.parent_process Processes.process_name Processes.process | `drop_dm_object_name(Processes)` | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`
```

**Defender KQL:**
```kql
DeviceProcessEvents
| where Timestamp > ago(7d)
| where InitiatingProcessFileName =~ "node.exe"
| where FileName in~ ("cmd.exe","powershell.exe","pwsh.exe","bash.exe","sh.exe","wmic.exe","mshta.exe","conhost.exe")
| where ProcessCommandLine has_any ("echo pwned","child_process","execSync","mainModule.require")
   or InitiatingProcessCommandLine has_any ("vm2","NodeVM","new VM(")
| project Timestamp, DeviceName, AccountName,
          ParentImage = InitiatingProcessFolderPath,
          ParentCmd = InitiatingProcessCommandLine,
          ChildImage = FolderPath,
          ChildCmd = ProcessCommandLine,
          InitiatingProcessParentFileName, SHA256
| order by Timestamp desc
```

### Vulnerable vm2 package (<=3.11.3) present in Defender software inventory

`UC_177_4` · phase: **weapon** · confidence: **Medium** · AI-generated for this article

**Defender KQL:**
```kql
union isfuzzy=true
(
  DeviceTvmSoftwareVulnerabilities
  | where CveId == "CVE-2026-47131"
  | project Timestamp, DeviceId, DeviceName, OSPlatform, SoftwareVendor, SoftwareName, SoftwareVersion, VulnerabilitySeverityLevel, RecommendedSecurityUpdate
),
(
  DeviceTvmSoftwareInventory
  | where SoftwareName has "vm2" and SoftwareVendor has_any ("npm","node","nodejs","openjs")
  | where SoftwareVersion matches regex @"^([0-2]\.|3\.([0-9]|10|11)(\.[0-3])?$)"
  | project Timestamp, DeviceId, DeviceName, OSPlatform, SoftwareVendor, SoftwareName, SoftwareVersion
)
| order by DeviceName asc
```

### Article-specific behavioural hunt — [GHSA / CRITICAL] CVE-2026-47131: vm2 has a Sandbox Escape issue

`UC_177_1` · phase: **exploit** · confidence: **High**

**Splunk SPL (CIM):**
```spl
``` Article-specific bespoke detection — [GHSA / CRITICAL] CVE-2026-47131: vm2 has a Sandbox Escape issue ```
| tstats `summariesonly` count earliest(_time) AS firstTime latest(_time) AS lastTime
    from datamodel=Endpoint.Processes
    where (Processes.process_name IN ("node.js"))
    by Processes.dest, Processes.user, Processes.process_name,
       Processes.process, Processes.parent_process_name, Processes.process_path
| `drop_dm_object_name(Processes)`
| `security_content_ctime(firstTime)`
| append [
| tstats `summariesonly` count
    from datamodel=Endpoint.Filesystem
    where Filesystem.action IN ("created","modified")
      AND (Filesystem.file_name IN ("node.js"))
    by Filesystem.dest, Filesystem.user, Filesystem.process_name,
       Filesystem.file_path, Filesystem.file_name
| `drop_dm_object_name(Filesystem)`
]
```

**Defender KQL:**
```kql
// Article-specific bespoke detection — [GHSA / CRITICAL] CVE-2026-47131: vm2 has a Sandbox Escape issue
// Hunts the actual binaries / paths / commandline fragments named
// in the article instead of a generic technique-class template.
DeviceProcessEvents
| where Timestamp > ago(30d)
| where (FileName in~ ("node.js"))
| project Timestamp, DeviceName, AccountName, FileName,
          FolderPath, ProcessCommandLine,
          InitiatingProcessFileName, InitiatingProcessCommandLine
| order by Timestamp desc

// File-creation events for the named binaries / paths
DeviceFileEvents
| where Timestamp > ago(30d)
| where ActionType in ("FileCreated","FileModified")
| where (FileName in~ ("node.js"))
| project Timestamp, DeviceName, AccountName, FolderPath,
          FileName, ActionType, InitiatingProcessFileName,
          InitiatingProcessCommandLine
| order by Timestamp desc
```

### IOC-driven hunts (use shared templates)

These are standard IOC-substitution hunts — the canonical SPL and KQL live once in [`_TEMPLATES.md`](../_TEMPLATES.md), so we don't repeat the same boilerplate on every CVE / hash / network-IOC briefing.

- **Asset exposure — vulnerability matches article CVE(s)** ([template](../_TEMPLATES.md#asset-exposure)) — phase: **recon**, confidence: **High**
  - CVE(s): `CVE-2026-47131`


## Why this matters

Severity classified as **CRIT** based on: CVE present, 5 use case(s) fired, 5 technique(s) inferred. Read the full article for actor attribution, tooling details, and any defanged IOCs in the body that aren't visible in the RSS summary.