CVE-2026-92957: vm2 (npm)

Should you act?

Critical, preconditions apply

Severe if exploited, but exploitation needs conditions that may not apply to you. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

Not in CISA KEV, but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
EPSS 0.5%, percentile 44: FIRST’s model estimates a 0.5% chance of exploitation activity in the next 30 days, higher than 44% of all scored CVEs (low). EPSS is a probability, not a verdict.
Needs an account (low (any account)). Exposure depends on who can log in.
Only applies if your dependency tree includes vm2 (npm) <= 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 through 3.11.6 does not normalize node:-prefixed builtin specifiers when evaluating user-supplied negative (deny) entries in a NodeVM wildcard require policy. Although NodeVM strips the node: prefix during require() resolution, negative wildcard entries are matched by exact string comparison against the canonical builtin names, so a policy such as new NodeVM({ require: { builtin: ['', '-node:childprocess'] } }) fails to deny the canonical childprocess module. Sandboxed code can therefore obtain the host childprocess builtin via require('childprocess') or require('node:childprocess'), gaining references to process-spawning APIs such as execSync and spawn, which is equivalent to host command-execution capability for untrusted sandbox code. Fixed in vm2 3.11.7.

From the GitHub advisory

Summary

NodeVM normalizes node:-prefixed builtin specifiers during require() resolution, but it does not normalize user-provided negative builtin entries in wildcard policy.

As a result, this configuration:

does not deny the canonical childprocess builtin. Sandboxed code can require both childprocess and node:childprocess, and receives the host module with process-spawning APIs such as execSync and spawn.

The safe proof below only checks module and function reachability. It does not execute any OS command.

Weakness type: CWE-269, CWE-284.

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

Affected and fixed versions

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

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

Severity scores

Scored by	CVSS	Score	Vector
VulnCheck	4.0	9.4 Critical	`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H`
VulnCheck	3.1	9.9 Critical	`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H`
GitHub	3.1	9.9	`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H`

Attack vector: network (remotely reachable)
Attack complexity: low
Attack requirements: none
Privileges required: low (any account)
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 poc, automatable no, technical impact total.
FIRST EPSS (model of 2026-10-21): 0.54% probability of exploitation activity in the next 30 days; percentile 44.

Timeline

2026-08-17 — erroneo.us brief: vm2: 22 Critical Sandbox Escapes, Fixed in 3.12.2
2026-09-17 — CVE record published by VulnCheck
2026-09-26 — CVE record last updated
2026-10-01 — GitHub-reviewed advisory GHSA-8686-vhfx-7r3j published (critical)

Sources and references

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