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Response snapshot Nov 6, 2026, 01:16 UTC

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VulnerabilityGHSA-m5w8-4gq2-6f8x

vm2: NodeVM `builtin: ['*']` exposes `os` and `dns` — process-wide observability reads AND writes that hijack the host (sibling class of GHSA-9g8x-92q2-p28f)

CWE: CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor) chained with CWE-732 (Incorrect Permission Assignment for Critical Resource) and CWE-285 (Improper Authorization) — same class the maintainer codified as Defense Invariant #13 in lib/builtin.

Published Updated

At a glance

Exploited
Not known
Severity
Not scored yet
Chance of exploitation
Not estimated
Sources
1 source

What to do

GitHub lists first patched versions: vm2: 3.11.6. Confirm the affected range and upgrade guidance in the exact advisory.

Read GitHub-reviewed advisory GHSA-m5w8-4gq2-6f8x (opens a new tab)

What happened

NodeVM builtin: ['*'] exposes os and dns — process-wide observability reads AND writes that hijack the host (sibling class of GHSA-9g8x-92q2-p28f)

CWE: CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor) chained with CWE-732 (Incorrect Permission Assignment for Critical Resource) and CWE-285 (Improper Authorization) — same class the maintainer codified as Defense Invariant #13 in lib/builtin.js and as Category 35 / GHSA-9g8x in docs/ATTACKS.md.

CVSS v3.1: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:L → 9.3 (Critical)

(Scope = Changed because the data being read and the state being written both belong to the host process, not the sandbox. Confidentiality = High because os.userInfo() returns host UID/GID/username/homedir + os.networkInterfaces() returns the full host network topology including container/VM interfaces with IPs and MAC addresses. Integrity = High because dns.

Continue reading

setServers() is a process-wide write that hijacks every subsequent DNS lookup the host makes — including outbound HTTP, telemetry, npm/registry, and any host code that uses fetch or URL-based fs paths. Privileges Required = None because the attacker controls sandbox code, which is the threat model NodeVM exists to mitigate.)

Summary

GHSA-9g8x-92q2-p28f closed the "process-wide observability builtins" class by adding diagnostics_channel, async_hooks, perf_hooks, and v8 to DANGEROUS_BUILTINS in lib/builtin.js. The fix's rationale (in the commit message and docs/ATTACKS.md Category 35) is general:

> Process-wide observability builtins. Unlike most Node builtins, these expose state of the *entire host process* rather than sandbox-local state — the vm2 boundary cannot usefully contain them because the data they surface […] belongs to the embedder. Even a readonly proxy that forwards every call to the host module is a working host-data exfiltration primitive.

Two builtins satisfying the same description were not added: os and dns. Both are reachable today under the documented builtin: ['*'] configuration; both expose host-process state that the vm.readonly() proxy cannot localise; and both have *write* APIs that mutate global host-process state from the sandbox (os.setPriority(), dns.setServers(), dns.setDefaultResultOrder()). dns.

setServers() in particular turns sandbox code into a process-wide DNS hijack primitive — strictly worse than every read-only leak that GHSA-9g8x added.

Adding os and dns to DANGEROUS_BUILTINS extends the same fix to the rest of the class. The existing isDangerousBuiltin(key) family-prefix matcher (added by GHSA-rp36-8xq3-r6c4) automatically catches node:os, node:dns, and node:dns/promises once the family names are present.

Affected

- vm2 v3.11.5 (current package.json version on main) and the unreleased [3.11.4] slot that ships GHSA-9g8x-92q2-p28f, GHSA-rp36-8xq3-r6c4, GHSA-r9pm-gxmw-wv6p, et al. - All NodeVM configurations that expand the builtin allowlist via '*' (the documented "full builtins" pattern) and have not manually appended -os, -dns exclusions — which is the recommended config in README and the test fixtures. - Reproduced on Node v22.12.0 with HEAD 7a1f510 of the audit checkout.

[A] — Source: the '*' wildcard expansion includes os and dns

lib/builtin.js:166-167:

const BUILTIN_MODULES = (nmod.builtinModules || Object.getOwnPropertyNames(process.binding('natives')))
 .filter(s => !s.startsWith('internal/') && !s.startsWith('_') && !isDangerousBuiltin(s));

isDangerousBuiltin resolves the current DANGEROUS_BUILTINS set (lib/builtin.js:83-139):

const DANGEROUS_BUILTINS = new Set([
 'module', 'worker_threads', 'cluster', 'vm', 'repl', 'inspector', 'process',
 'trace_events', 'wasi',
 // GHSA-9g8x-92q2-p28f:
 'diagnostics_channel', 'async_hooks', 'perf_hooks', 'v8'
]);

os and dns are absent. Under builtin: ['*'] they are admitted into the user-visible builtin map and loaded via the default vm.readonly(hostRequire(key)) path (lib/builtin.js:230):

builtins.set(key, special ? special : vm => vm.readonly(hostRequire(key)));

The readonly proxy forwards every method call to the host realm. For modules whose entire purpose is to read or mutate host-process state, the readonly wrap protects nothing — same observation the GHSA-9g8x commit message makes for v8/perf_hooks.

[B] — os: host-process READS the bridge cannot localise

os.userInfo() returns the host process owner (uid, gid, username, homedir, shell). os.networkInterfaces() returns the host's full network topology including container/VM interfaces with their IPs and MAC addresses. os.hostname() returns the host deployment identity. os.loadavg() / os.uptime() / os.freemem() / os.totalmem() expose host-wide telemetry.

The data source is the host kernel and the host process — the sandbox's vm.readonly() proxy cannot make these calls "sandbox-local" any more than it can for perf_hooks.performance.getEntriesByType('mark'). Same class as the four builtins GHSA-9g8x added.

[C] — os: host-process WRITE via os.setPriority()

os.setPriority([pid, ]priority) invokes setpriority(2) on the host process. With pid = 0 (the default) the sandbox lowers — or, if the host has CAP_SYS_NICE, raises — the priority of the host process. Effect persists after the sandbox call returns; the host has no notification.

Strictly worse than the read-only v8 / perf_hooks family because it's a *mutation* of host state, not just an observation.

[D] — dns: host-process READS

dns.lookup(hostname, cb) and dns.resolve(hostname, cb) perform DNS queries from the host network identity. The query leaves the host process and lands at whatever DNS resolver the host is configured to use, which sees the host's source IP and the queried name. For deployments behind corporate DNS or per-tenant resolvers, this is a

Affected package ranges reported by GitHub: vm2: <= 3.11.5

Related technology

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Sources

  1. Primary source

    GitHub-reviewed advisory GHSA-m5w8-4gq2-6f8x (opens a new tab)

    The public advisory supplies the description, affected package/version ranges, and any listed CVSS metric. GitHub review is not local review.

    Published Checked

  2. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-m5w8-4gq2-6f8x, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

Cite this record

For factual claims, cite the primary sources above; cite KEVWire for its compilation, dates, and classifications.

APA

KEVWire. (2026, November 5). vm2: NodeVM `builtin: ['*']` exposes `os` and `dns` — process-wide observability reads AND writes that hijack the host (sibling class of GHSA-9g8x-92q2-p28f). https://kevwire.com/record/GHSA-m5w8-4gq2-6f8x

MLA

"vm2: NodeVM `builtin: ['*']` exposes `os` and `dns` — process-wide observability reads AND writes that hijack the host (sibling class of GHSA-9g8x-92q2-p28f)." KEVWire, 5 Nov. 2026, kevwire.com/record/GHSA-m5w8-4gq2-6f8x.

Chicago

KEVWire. "vm2: NodeVM `builtin: ['*']` exposes `os` and `dns` — process-wide observability reads AND writes that hijack the host (sibling class of GHSA-9g8x-92q2-p28f)." Last modified November 5, 2026. https://kevwire.com/record/GHSA-m5w8-4gq2-6f8x.

Evidence summary (plain text)

vm2: NodeVM `builtin: ['*']` exposes `os` and `dns` — process-wide observability reads AND writes that hijack the host (sibling class of GHSA-9g8x-92q2-p28f) (Aug 17, 2026).
CWE: CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor) chained with CWE-732 (Incorrect Permission Assignment for Critical Resource) and CWE-285 (Improper Authorization) — same class the maintainer codified as Defense Invariant #13 in lib/builtin.js and as Category 35 / GHSA-9g8x in docs/ATTACKS.md.

CVSS v3.1: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:L → 9.3 (Critical)

(Scope = Changed because the data being read and the state being written both belong to the host process, not the sandbox.
Sources:
GitHub-reviewed advisory GHSA-m5w8-4gq2-6f8x: https://github.com/advisories/GHSA-m5w8-4gq2-6f8x
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc
Record ID: GHSA-m5w8-4gq2-6f8x.
Record origin: Ingested record.
AI evidence: Not assessed.
Known exploitation: Not assessed.
Zero-day status: Not assessed. KEV membership alone does not establish zero-day status.
About this data

This record was ingested from a data source. Retrieved: Nov 6, 2026, 01:15 UTC. Ingestion is not an independent editorial investigation.

A CISA KEV listing documents known exploitation, not necessarily a zero-day; absence from the catalog does not prove a vulnerability has never been exploited.

Technology tags indicate possible relevance, not verified exposure. Confirm the affected product, version, and configuration against your own inventory; KEVWire does not scan your systems.

A personal reading checklist on this device, not verified remediation.

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