CVE-2026-93605: vm2 contains a sandbox escape vulnerability

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 0.7%, percentile 54: FIRST’s model estimates a 0.7% chance of exploitation activity in the next 30 days, higher than 54% of all scored CVEs (moderate). 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) <= 3.12.0, fixed in 3.12.1. 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 NodeVM versions before 3.12.1 contain a sandbox escape vulnerability where the DANGEROUSBUILTINS denylist omits childprocess despite blocking other host-spawning modules. Attackers can require childprocess and execute arbitrary commands on the host system when NodeVM is configured with builtin:[''] or explicit childprocess allowance.

From the GitHub advisory

vm2 NodeVM versions before 3.12.1 contain a sandbox escape vulnerability where the DANGEROUSBUILTINS denylist omits childprocess despite blocking other host-spawning modules. Attackers can require childprocess and execute arbitrary commands on the host system when NodeVM is configured with builtin:[''] or explicit childprocess allowance.

This fork hardens NodeVM with a DANGEROUSBUILTINS denylist that blocks host‑code‑reaching core modules even when the sandbox requests builtin:[''] or names them explicitly — the list contains module, workerthreads, cluster, vm, repl, inspector, process, traceevents, wasi, diagnosticschannel, asynchooks, perfhooks, v8, os, dns, and test. It omits childprocess — the single most direct command‑execution primitive. As a result, a sandbox running under require:{builtin:['']} (or the fork's own documented ['','-http','-net',…] subtract pattern) can require('childprocess').execSync(...) and execute arbitrary commands on the host. The omission is internally inconsistent: cluster is denied with the explicit rationale "cluster.fork() spawns a host child process running attacker‑controlled code," yet childprocess — which spawns host processes more directly — is not.

Details lib/builtin.js: - DANGEROUSBUILTINS (lines 83‑179) — the Set of denied builtins. childprocess does not appear anywhere in it. - isDangerousBuiltin(key) (lines 185‑195) — strips node: prefixes and applies family‑prefix matching against DANGEROUSBUILTINS. Returns false for childprocess. - BUILTINMODULES (lines 209‑210) — the source list that the '' wildcard expands to — is builtinModules.filter(s => !s.startsWith('internal/') && !s.startsWith('') && !isDangerousBuiltin(s)). Because isDangerousBuiltin('childprocess') is false, childprocess remains in ''. - addDefaultBuiltin (the explicit‑name path) likewise rejects only isDangerousBuiltin names, so builtin:['childprocess'] is admitted as well.

The module returned is the real host childprocess (default require.context is "host"), so execSync/exec/spawn/fork run with full host authority. The denylist's own comment (lines 42‑44) states these primitives "must NEVER be reachable from the sandbox, even when the user requests '' or explicitly names them" —…

Weakness type: CWE-693, CWE-913.

Product: vm2 (npm) · Assigned by: VulnCheck · Published: 2026-09-18

Affected and fixed versions

Severity scores

• 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): 0.73% probability of exploitation activity in the next 30 days; percentile 54.

Timeline

• 2026-08-17 — erroneo.us brief: vm2: 22 Critical Sandbox Escapes, Fixed in 3.12.2
• 2026-09-18 — CVE record published by VulnCheck
• 2026-09-21 — CVE record last updated
• 2026-10-07 — GitHub-reviewed advisory GHSA-pq68-rvw4-xp4r published (critical)

Sources and references

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

Vendor and project advisories, patches

1. GitHub Security Advisory (GHSA-pq68-rvw4-xp4r) github.com

Vulnerability records

1. GitHub Advisory GHSA-pq68-rvw4-xp4r github.com
2. CVE.org record CVE-2026-93605 cve.org
3. NVD entry CVE-2026-93605 nvd.nist.gov

Other references from the CVE record and advisory

1. VulnCheck Advisory: vm2 NodeVM before 3.12.1 Remote Code Execution via child_process vulncheck.com

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