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vm2: NodeVM builtin denylist bypass via fs/promises despite -fs, allowing host filesystem writes

Type: advisorySource: OSV1 source record

## Summary NodeVM's builtin wildcard policy can allow sandboxed code to access `fs/promises` even when the embedder denies `fs`. With the following configuration: ```js require: { builtin: ['*', '-fs', '-child_process'] } ``` `require('fs')` and `require('child_process')` are blocked, but `require('fs/promises')` and `require('node:fs/promises')` are still available. This allows sandboxed code to create and write files on the host filesystem through the promise-based filesystem API. ## Affected Mode NodeVM. ## Affected Configuration ```js new NodeVM({ require: { builtin: ['*', '-fs', '-child_process'] } }); ``` This affects configurations where users rely on negative builtin entries such as `-fs` to deny filesystem access while using the `'*'` builtin wildcard. ## Affected Files / Functions - `lib/builtin.js` - `DANGEROUS_BUILTINS` - `BUILTIN_MODULES` - `makeBuiltinsFromLegacyOptions` - `addDefaultBuiltin` - `lib/resolver.js` - `Resolver.resolve` - `Resolver.loadBuiltinModule` - `lib/setup-node-sandbox.js` - `requireImpl` ## Root Cause `lib/builtin.js` builds `BUILTIN_MODULES` from Node's builtin module list and filters dangerous/default-denied modules. In wildcard mode, negative entries are checked by exact name: ```js if (builtins.indexOf(`-${name}`) === -1) { addDefaultBuiltin(res, name, hostRequire); } ``` This means `-fs` removes only the exact builtin named `fs`. It does not remove builtin subpaths such as `fs/promises`. There is also inconsistent `node:` prefix handlin

Announced Group revision 1
Original source ↗

GHSA-6rh5-qq4q-97xh

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: osv:GHSA-6rh5-qq4q-97xh

vm2

Source reference: /affected/0/package/name

Affected versions
Not stated in this record
Fixed versions
3.11.7

Source reference: /affected/0/ranges

Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "ranges": [
      {
        "type": "SEMVER",
        "events": [
          {
            "introduced": "0"
          },
          {
            "fixed": "3.11.7"
          }
        ]
      }
    ],
    "package": {
      "name": "vm2",
      "purl": "pkg:npm/vm2",
      "ecosystem": "npm"
    },
    "database_specific": {
      "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-6rh5-qq4q-97xh/GHSA-6rh5-qq4q-97xh.json",
      "last_known_affected_version_range": "<= 3.11.6"
    }
  }
]
Related CVEs
CVE-2026-92958

Source reference: /aliases

Publisher severity

high

Source reference: /database_specific/severity

Event
#61270 · Revision 1
Added to Heist Feed
Publisher date
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