# CVE-2026-93606: vm2 before 3.12.1 Sandbox Escape via Promise Symbol.species

> Sandboxed code can escape the vm2 sandbox and execute arbitrary code on the host by exploiting Promise Symbol.species handling.

- **Severity:** Critical 10.0 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 18 Sep 2026
- **Updated:** 18 Sep 2026
- **Also known as:** GHSA-6454-5x88-m6jw, GHSA-q84h-7qfg-c6j8

## What is CVE-2026-93606?

CVE-2026-93606 is a critical code injection vulnerability in patriksimek vm2, published on 18 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

vm2 (npm) versions 3.12.0 and earlier contain a sandbox escape in `VM` and `NodeVM`. When an embedder exposes a host API that returns a host-realm Promise, the bridge's rejection sanitizer (hostPromiseSanitizeReject / makeSanitizedPromiseCallback / normalizeHostPromiseCallbacks in lib/bridge.js) only wraps `then`/`catch` rejection slots that hold a function, and the sandbox-side `Symbol.species`/`.then` neutralization is installed only on the sandbox intrinsic `Promise.prototype`, so it never applies to a host Promise. Code running inside the sandbox can overwrite `p.constructor[Symbol.species]` on the host Promise and then call `p.then()` with no `onRejected` handler; V8 substitutes its internal Thrower, which re-throws the raw host rejection value into a resolve/reject closure captured by the attacker. This delivers an unsanitized, fully functional bridge proxy of the host object to sandboxed code, bypassing handleException and hostPromiseSanitizeReject. If the rejection value is host-pivotable (for example a host `process` object), this results in arbitrary code execution on the host. Fixed in 3.12.1.

Weakness: CWE-693 (Protection Mechanism Failure)

## Which versions are affected by CVE-2026-93606?


## How do I fix CVE-2026-93606?

No fix has been published for CVE-2026-93606 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-93606 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-93606 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-93606 and fix it if it is affected.

What it is: CVE-2026-93606 is a critical code injection vulnerability in patriksimek vm2, published on 18 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-93606 exists.

Affected product: patriksimek vm2. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-93606/ (Markdown: https://insights.sbomify.com/CVE-2026-93606/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-93606
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-93606
- OSV: https://osv.dev/vulnerability/CVE-2026-93606

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-93606/
Summaries are generated and may contain mistakes; the official description above is the record.