CVE-2026-92956: vm2 (npm)

Should you act?

Critical and remotely reachable

No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
EPSS 0.6%, percentile 47: FIRST’s model estimates a 0.6% chance of exploitation activity in the next 30 days, higher than 47% of all scored CVEs (low). EPSS is a probability, not a verdict.
Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
Only applies if your dependency tree includes vm2 (npm) >= 3.10.1, <= 3.11.6, fixed in 3.11.7. Check your lockfile, including transitive dependencies.
Editorial verdict: Check exposure. vm2: 22 Critical Sandbox Escapes, Fixed in 3.12.2 — If anything outside your trust boundary can get code into vm2, upgrade to 3.12.2 today and plan to move that code out of process; if vm2 only runs your own code, upgrade on a normal cycle.

What it is

vm2 versions 3.10.1 through 3.11.6 contain a sandbox escape reachable from a default new VM() sandbox when running on Node.js 26. WebAssembly.compileStreaming and WebAssembly.instantiateStreaming can produce a raw host-realm Promise that rejects with a host-realm error object; by controlling Symbol.species via Promise.prototype.finally, sandbox code receives that raw host error, walks from the host error constructor to the host Function constructor, and recovers the real host process object, gaining host Node.js capabilities (e.g. access to host modules such as fs) in the context of the process running the sandbox. No NodeVM, require permission, host object injection, or otherwise unsafe configuration is required. This is a bypass of the fix for GHSA-6j2x-vhqr-qr7q, which removed the JSPI entry points WebAssembly.promising and WebAssembly.Suspending. The issue is fixed in 3.11.7.

From the GitHub advisory

Summary

There is a sandbox escape in vm2 3.11.5 / current HEAD when it is used on Node.js 26. The issue is reachable from a default new VM() sandbox. No NodeVM, require permission, host object injection, or intentionally unsafe configuration is required.

The escape is a patch-bypass of the same security invariant addressed by GHSA-6j2x-vhqr-qr7q. The earlier fix removed the JSPI entry points WebAssembly.promising and WebAssembly.Suspending, because those APIs exposed a Promise path whose host-realm Promise.prototype was not intercepted by vm2's Promise hardening or bridge layer.

The same unsafe class remains reachable through WebAssembly.compileStreaming and WebAssembly.instantiateStreaming. On Node 26, these streaming APIs can produce a raw host-realm Promise path that rejects with a host-realm error. By controlling Symbol.species through Promise.prototype.finally, sandbox code can receive that raw host error object, walk from the host error constructor to the host Function constructor, and recover the real host process object.

The proof of concept demonstrates this by first showing that direct access to process, require, and constructor-based escapes are blocked in the same default VM. It then reaches the host process, verifies that the recovered pid matches the parent Node process, and writes a harmless marker file through host fs.

Weakness type: CWE-693, CWE-913.

Product: vm2 (npm) · Assigned by: VulnCheck · Published: 2026-09-17

Affected and fixed versions

Ecosystem	Package	Vulnerable	First fixed
npm	`vm2`	>= 3.10.1, <= 3.11.6	3.11.7

Vendor	Product	Affected versions (per CVE record)
patriksimek	vm2	3.10.1 < 3.11.7

Severity scores

Scored by	CVSS	Score	Vector
VulnCheck	4.0	10 Critical	`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H`
VulnCheck	3.1	10 Critical	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H`
GitHub	3.1	10.0	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H`

Attack vector: network (remotely reachable)
Attack complexity: low
Attack requirements: none
Privileges required: none (no login)
User interaction: none

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
CISA SSVC assessment: exploitation none, automatable yes, technical impact total.
FIRST EPSS (model of 2026-10-21): 0.59% probability of exploitation activity in the next 30 days; percentile 47.

Timeline

2026-08-17 — erroneo.us brief: vm2: 22 Critical Sandbox Escapes, Fixed in 3.12.2
2026-09-17 — CVE record last updated
2026-09-17 — CVE record published by VulnCheck
2026-10-05 — GitHub-reviewed advisory GHSA-wjwh-qqvp-g4p4 published (critical)

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.