vm2 before 3.12.2 does not apply its Buffer backing-store ownership invariant (byteOffset === 0 and buffer.byteLength === length) to Buffers returned from host builtin modules. When an application explicitly exposes Node's zlib module through NodeVM's builtin allowlist (require: { builtin: ['zlib'] }), zlib.deflateSync can return a Buffer backed by Node's shared small-buffer pool whose .buffer is the entire pool. Untrusted guest code can construct a full-width view of that ArrayBuffer (Buffer.from(result.buffer, 0, result.buffer.byteLength)) to read and modify bytes belonging to unrelated host buffers, disclosing and corrupting host-realm memory across the sandbox boundary.
vm2 before 3.12.2 does not apply host-side Promise rejection handling in the sandbox-to-host construct trap. In BaseHandler, the apply trap calls markHostPromiseHandled() on the returned value, but the adjacent construct path returns the result of Reflect.construct without the same sanitization. If an embedder exposes a constructable host function whose constructor returns a native rejected Promise, an untrusted script executed via VM.run can invoke it with `new` and ignore the result; the rejected host Promise crosses the bridge unhandled and, under Node's strict unhandled-rejection policy, is promoted to an uncaught exception that terminates the host process.
vm2 before 3.12.2 contains an authorization bypass in the NodeVM external-module resolver. When an embedder configures `require.external` with a custom resolver (and `context: 'host'`), `LegacyResolver.customResolve` in lib/resolver-compat.js records the resolved module directory in `this.externals` as `new RegExp('^' + escapeRegExp(resolvedPath))`, without requiring a path separator or end-of-string boundary. Untrusted guest code can therefore require the allowlisted module (e.g. `foo`) and then require the absolute path of a non-allowlisted sibling whose path merely shares the resolved prefix (e.g. `.../node_modules/foo2/index.js`); the sibling passes `isPathAllowedForModule` and is loaded through `hostRequire`, so its top-level code runs in the host process before the exports are wrapped with `vm.readonly`, resulting in a sandbox escape and arbitrary code execution in the host context.
vm2 NodeVM versions prior to 3.12.1 have a critical sandbox escape vulnerability. The vulnerability arises because the denylist of dangerous built-in modules omits child_process, allowing attackers to require this module and execute arbitrary commands on the host system when NodeVM is configured with builtin:['*'] or explicitly allows child_process.
vm2 NodeVM versions before 3.12.1 have a sandbox escape vulnerability due to an incomplete denylist of dangerous built-in modules. The denylist omits 'child_process', allowing sandboxed code configured with require:{builtin:['*']} or explicit 'child_process' allowance to execute arbitrary commands on the host system. This leads to full host remote code execution (RCE) from within the sandbox.
vm2 (npm) versions 3.12.0 and earlier contain a sandbox escape in `VM` and `NodeVM`. When an embedder exposes a host API that returns a host-realm Promise, the bridge's rejection sanitizer (hostPromiseSanitizeReject / makeSanitizedPromiseCallback / normalizeHostPromiseCallbacks in lib/bridge.js) only wraps `then`/`catch` rejection slots that hold a function, and the sandbox-side `Symbol.species`/`.then` neutralization is installed only on the sandbox intrinsic `Promise.prototype`, so it never applies to a host Promise. Code running inside the sandbox can overwrite `p.constructor[Symbol.species]` on the host Promise and then call `p.then()` with no `onRejected` handler; V8 substitutes its internal Thrower, which re-throws the raw host rejection value into a resolve/reject closure captured by the attacker. This delivers an unsanitized, fully functional bridge proxy of the host object to sandboxed code, bypassing handleException and hostPromiseSanitizeReject. If the rejection value is host-pivotable (for example a host `process` object), this results in arbitrary code execution on the host. Fixed in 3.12.1.
vm2 through 3.12.0 exposes Node.js's crypto.setFips() function to untrusted guest code when an embedder explicitly allowlists the crypto builtin for a NodeVM (require.builtin: ['crypto']). The builtin sanitizer (sanitizeCryptoModule in lib/builtin.js) replaces crypto.setEngine but leaves crypto.setFips callable, and the readonly wrapper used to expose the host module does not localize side effects of forwarded host functions. Guest code can therefore call crypto.setFips() to change the FIPS mode of the entire host process; the modified mode is subsequently observed by trusted host code (crypto.getFips() changed from 0 to 1 in the reported test), crossing the NodeVM isolation boundary. Fixed in vm2 3.12.1.
vm2 through 3.12.0 (fixed in 3.12.1) does not correctly handle a nullish `this` receiver in the apply trap of its bridge (lib/bridge.js): when sandboxed code calls a host-provided non-strict (sloppy-mode) function without a receiver — e.g. `fn()`, a detached method, `fn.call()`, `fn.apply(undefined)`, `Reflect.apply(fn, undefined, [])`, or `fn.bind()()` — the undefined receiver is passed straight through to the host call, and V8 substitutes the host realm's global object for `this`. vm2 then wraps and returns that object to the sandbox, giving sandboxed script a live proxy of the host global. This allows a complete sandbox escape: untrusted script can reach `process` and execute arbitrary code/commands on the host (for example via `process.getBuiltinModule('child_process').execSync`). Exploitation requires that the embedding application expose at least one non-strict host function to the sandbox; strict-mode and ES module host functions are not affected.
A vulnerability in patriksimek vm2 versions before 3.11.2 allows attackers to access an internal global variable VM2_INTERNAL_STATE_DO_NOT_USE_OR_PROGRAM_WILL_FAIL via globalThis. This improper restriction exposes sensitive sandbox internals. The issue is tracked as CVE-2026-92963 and has a medium severity rating with a CVSS score of 6.9.
vm2 is a sandbox for running untrusted JavaScript. In vm2 versions up to and including 3.11.3, the defaultSandboxPrepareStackTrace function in lib/setup-sandbox.js builds its output array using prototype-walking index assignment (lines[lines.length] = value) rather than a prototype-bypassing define-property primitive. Because this bridge-internal array is allocated in the sandbox realm, code inside the sandbox can install an accessor on Array.prototype for the relevant index; the accessor is then invoked whenever the sandbox reads error.stack (or otherwise triggers Error.prepareStackTrace), allowing sandbox code to observe and intercept each stack-trace line written by the bridge. The same pattern is used in the error-handling (catch) branch. The values written are formatted strings only, so the practical impact is limited to an information side channel and a violation of vm2's bridge-container defense invariant rather than a sandbox escape; the vendor rates the issue Low. The issue is fixed in vm2 3.11.4, which installs each entry as an own data property via Reflect.defineProperty.
vm2 before 3.11.6 fails to enforce bufferAllocLimit on ArrayBuffer, SharedArrayBuffer, and TypedArray constructors, allowing attackers to allocate arbitrary host memory. Attackers can bypass the buffer allocation cap by using these V8 intrinsics to exhaust host process memory and trigger out-of-memory conditions.
vm2 before 3.11.6 fails to restrict access to os and dns builtins under the builtin: ['*'] configuration, allowing sandbox code to read host process identity and network topology. Attackers can invoke dns.setServers() to hijack the host process DNS resolver globally, redirecting all subsequent host DNS queries through an attacker-controlled resolver.
vm2 before 3.11.8 does not fully enforce the allowAsync: false option in VM and NodeVM. While localPromise.prototype.then is replaced with a handler that throws 'Async not available', the sandbox's Promise static methods (Promise.resolve, Promise.all, Promise.race, Promise.any, and Promise.allSettled) still assimilate attacker-supplied thenables: native promise resolution performs PromiseResolveThenableJob and invokes the sandboxed code's then method in a microtask without passing through the patched then, so the async restriction is never applied. As a result, sandboxed script can schedule work that runs after VM.run() or NodeVM.run() has returned and outside the configured timeout, continuing to execute after the host believes execution is complete.
CVE-2026-92958 is a high-severity vulnerability in the patriksimek vm2 library up to version 3.11.6. It involves an improper privilege management issue where the builtin-module denylist in NodeVM can be bypassed. Specifically, when using a builtin wildcard with negative entries to restrict modules, subpaths of denied modules such as fs/promises remain accessible. This allows sandboxed code to require and use promise-based filesystem APIs despite restrictions. The vulnerability enables unauthorized file creation and modification operations. The issue is fixed in vm2 version 3.11.7.
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:child_process'] } })` fails to deny the canonical `child_process` module. Sandboxed code can therefore obtain the host `child_process` builtin via `require('child_process')` or `require('node:child_process')`, 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.
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.
vm2 before 3.11.8 contains a sandbox escape vulnerability in NodeVM that allows attackers to access the host __proto__ getter/setter through console._stdout and console._stderr. Attackers can overwrite EventEmitter.prototype.emit and trigger process events to execute code with process context, bypassing code generation restrictions.
CVE-2026-92954 is a critical vulnerability in the vm2 sandbox library for Node.js versions 3.10.0 through 3.11.7. It involves improper handling of Promises returned from the host environment into the sandbox, which can cause unhandled Promise rejections in the host process. This may lead to the termination of the host Node.js process. The issue is fixed in version 3.11.8.
CVE-2026-92953 is a critical vulnerability in patriksimek vm2 affecting versions 3.11.0 up to but not including 3.11.8. The flaw allows attackers to mutate host TypedArray and ArrayBuffer prototypes from within the sandbox environment, leading to host-created typed arrays inheriting attacker-controlled properties after VM.run() execution.
vm2 versions 3.11.4 through 3.11.6 incompletely filter Node.js registered internal symbols across the sandbox boundary. The extraction filters in lib/setup-sandbox.js and the cross-realm symbol checks and write traps in lib/bridge.js use a fixed list of known dangerous registered symbols that omits nodejs.stream.disturbed and nodejs.stream.errored, which are exposed on host WebStream prototypes on newer Node.js releases (validated on Node.js v25.8.0). When the embedder exposes a host WebStream object and the host stream/web module to the sandbox, sandbox code can obtain the real host symbols via Object.getOwnPropertySymbols(streamWeb.ReadableStream.prototype) and use them as write keys on host stream objects, corrupting host-visible stream state — for example making stream.Readable.isDisturbed() return false for an already-consumed stream. This can bypass host logic that relies on Node's public stream-state helpers to enforce one-shot body consumption, reject errored streams, or decide whether a stream is safe to hand to another component. It is not a host code-execution primitive in the reported proof of vulnerability. This is an incomplete fix for the earlier nodejs.* symbol filtering issue. Fixed in vm2 3.11.7.