vm2 before 3.11.8 Sandbox Escape RCE via AggregateError

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 before 3.11.8 contains an incomplete fix for Error.cause sanitization that allows sandbox escape when revisited host-wrapped AggregateError objects are caught within a single exception handler traversal. Attackers can exploit cycle detection bypass in handleException to access unsanitized host proxies embedded in the errors array, enabling full remote code execution and process information disclosure from the sandbox.

Source published

17 Sep 2026 13:46:00 UTC

Source modified

17 Sep 2026 14:27:25 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

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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: cve-program · CVE Program Terms of Use. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 4.0 · 9.5 CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H

CVSS 3.1 · 9.0 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H

vm2 before 3.11.8 contains an incomplete fix for Error.cause sanitization that allows sandbox escape when revisited host-wrapped AggregateError objects are caught within a single exception handler traversal. Attackers can exploit cycle detection bypass in handleException to access unsanitized host proxies embedded in the errors array, enabling full remote code execution and process information disclosure from the sandbox.

Source published

Sep 17, 2026, 1:46:00 PM (timezone not stated)

Source modified

Sep 17, 2026, 2:27:25 PM (timezone not stated)

Observed here

11 Nov 2026 18:10:29 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 4.0 · 9.5 CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H

vm2 before 3.11.8 contains an incomplete fix for Error.cause sanitization that allows sandbox escape when revisited host-wrapped AggregateError objects are caught within a single exception handler traversal. Attackers can exploit cycle detection bypass in handleException to access unsanitized host proxies embedded in the errors array, enabling full remote code execution and process information disclosure from the sandbox.

Source published

17 Sep 2026 14:17:57 UTC

Source modified

17 Sep 2026 15:17:00 UTC

Observed here

25 Oct 2026 16:19:22 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 4.0 · [email protected] · Secondary · 9.5 CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

CVSS 3.1 · [email protected] · Secondary · 9.0 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H

## Duplicate Advisory This advisory has been withdrawn because it is a duplicate of GHSA-x965-fc75-jpqh. This link is maintained to preserve external references. ## Original Description vm2 before 3.11.8 contains an incomplete fix for Error.cause sanitization that allows sandbox escape when revisited host-wrapped AggregateError objects are caught within a single exception handler traversal. Attackers can exploit cycle detection bypass in handleException to access unsanitized host proxies embedded in the errors array, enabling full remote code execution and process information disclosure from the sandbox.

Source published

17 Sep 2026 15:32:14 UTC

Source modified

5 Oct 2026 22:45:04 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

Original source record · Cite this exact observation · Complete original publisher JSON

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:H/PR:N/UI:N/S:C/C:H/I:H/A:H

CVSS_V4 · CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Publisher rating · CRITICAL

## Summary vm2 `3.11.6` (this fork's latest release) contains an incomplete-fix bypass of the Error.cause host-reference sanitization added in GHSA-m283-3h24-438v (commit `7e3faaf`). Sandbox code that catches a host-wrapped `AggregateError` which is *revisited within a single `handleException` traversal* (self-cycle, mutual-cycle, or the same host aggregate referenced twice in `errors[]`) receives a live, unsanitized host proxy inside the "sanitized" `errors[]`, yielding full host RCE on the throw channel that the fix and Defense Invariant #3 explicitly promise to sanitize. ## Root Cause `handleException` (`lib/setup-sandbox.js`) breaks recursion cycles at line 1819 with `if (apply(localWeakMapGet, visited, [e])) return e;` — returning the RAW host carrier on revisit. For plain-`Error` carriers this is safe because `sanitizeErrorCause`/`sanitizeHostOwnProps` seal the host object **in place** on first visit. But `sanitizeAggregateError` (~1954-1972) snapshot-and-rebuilds host-wrapped carriers into a fresh `LocalAggregateError` and does NOT seal the original in place. When such a carrier is revisited within one traversal, line 1819 hands back the still-live raw host proxy, which the rebuild re-embeds via `sanitizedArr[sanitizedArr.length] = handleException(item, visited)` (line 1965) into the "sanitized" `errors[]`. ## Impact Full host RCE (`child_process.execSync`) and host info disclosure (`process.env`, `.pid`) from within the vm2 sandbox — a complete sandbox escape on the caught-exception (throw) channel. ## Proof of Concept ```js const {VM} = require('vm2'); const vm = new VM({ sandbox: { hostThrow(){ const shared = new AggregateError([], 'shared'); shared.leak = process; // incidental host ref throw new AggregateError([shared, shared], 'all failed'); // same host obj twice }}}); console.log(vm.run(` try { hostThrow(); } catch (e) { e.errors[1].leak.mainModule.require('child_process').execSync('id').toString(); }`)); // -> uid=1000(...) host RCE ``` Confirmed vectors (all return real `id` output): AggregateError self-cycle (`agg.errors=[agg]; agg.leak=process`), duplicate-in-array (`[shared,shared]`), mutual-cycle (`a.errors=[b]; b.errors=[a]`), and nested mutual/duplicated host sub-AggregateError. ## Attack Chain 1. **Entry** — embedder exposes a host function the sandbox invokes; it throws a host-wrapped `AggregateError` carrying a host reference in a rebuild-surviving slot plus a revisit trigger (`agg.errors=[agg]; agg.leak=process`). *Guard:* none at entry (throwing from an exposed host fn is normal). *Bypass proof:* same entry class as GHSA-m283-3h24-438v (embedder-exposed throwing fn, `docs/ATTACKS.md` Category 38), accepted in scope. 2. **Caught-exception sanitizer** — sandbox `try{hostThrow()}catch(e){…}`; transformer routes `e` through `handleException`. *Guard:* Defense Invariant #3 (Aggregate/Suppressed nested fields sanitized with cycle detection). *Bypass proof:* `handleException(agg)` marks `agg` visited (1820); proto-walk routes to `sanitizeAggregateError` (1865); host-wrapped branch reads `agg.errors` and calls `handleException(agg, visited)` on element 0 (1965); that inner call hits `visited.get(agg)===true` → `return e` (1819) → raw `agg` proxy pushed into `sanitizedArr` → becomes `newAgg.errors[0]`. The rebuild does NOT seal `agg` in place, so the returned proxy is fully live. 3. **Sink** — `e.errors[0].leak.mainModule.require('child_process').execSync('id')`. *Guard:* bridge `get` wraps host values. *Bypass proof:* the wrap is functional, not capability-restricting; instrumented trace shows `e.errors[0].isProxy===true` yet the chain executes and returns real `uid=1000(ubuntu)...`. 4. **Impact** — host RCE with host privileges; also `process.env`/`.pid` disclosure. ## Bypass Evidence Executed on node v22.23, vm2 `3.11.6`: - Baseline vector `throw new Error('x',{cause:process})` (plain Error `.cause`) → BLOCKED - Plain Error own-prop `e.leak=process` (non-cyclic) → BLOCKED - Non-cyclic host `AggregateError` w/ own-prop or single host sub-error leak → BLOCKED - **AggregateError self-cycle / duplicate-in-array / mutual-cycle / nested → RCE (`uid=1000(ubuntu)…`)** Every non-cyclic shape and the exact baseline `cause` vector are blocked; only the revisited host `AggregateError` leaks — proving the fix is present but this input shape evades it (INCOMPLETE FIX BYPASS, not a duplicate). Instrumented trace: `outerLeakType="undefined"` (outer rebuilt safe), `isErrors0Proxy=true` (element 0 is a live host proxy), `rce=uid=1000(ubuntu)…`. ## Affected Versions `<= 3.11.6`. The bug exists from the sanitization fix (`7e3faaf`, tag `3.11.6`) onward — an incomplete-fix bypass exists only where the fix exists. `git diff 3.11.6 HEAD -- lib/setup-sandbox.js` is empty (HEAD identical). ## Scope Note This advisory covers the **AggregateError** family only. A `SuppressedError` variant does NOT reproduce (`se.error` returns undefined; RCE blocked) and is excluded. ## Suggested Fix On the cycle short-circuit (line 1819), return the memoized sandbox-realm *replacement* (keyed in `visited`) rather than the raw carrier; OR seal host-wrapped `AggregateError`/`SuppressedError` carriers in place *before* recursing into sub-errors, mirroring the plain-carrier `sanitizeHostOwnProps` invariant. --- Reported by **zx (Jace)** — GitHub: @manus-use

Source published

5 Oct 2026 22:38:04 UTC

Source modified

5 Oct 2026 22:45:06 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

Original source record · Cite this exact observation · Complete original publisher JSON

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:H/PR:N/UI:N/S:C/C:H/I:H/A:H

CVSS_V4 · CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H

Publisher rating · CRITICAL