Security Digest · Vulnerability record
CVE-2026-47698: vm2: Sandbox Breakout Using Dangerous Host Proto Mutators
vm2 is an open source vm/sandbox for Node.js.
CVSS 9.8 Critical EPSS 1.0% · p62 Check exposure
Should you act?
Critical and remotely reachable
No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.
- Not in CISA KEV, but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
- EPSS 1.0%, percentile 62: FIRST’s model estimates a 1.0% chance of exploitation activity in the next 30 days, higher than 62% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes
vm2(npm) <= 3.11.5, fixed in 3.11.6. Check your lockfile, including transitive dependencies. - Editorial verdict: Check exposure. vm2: 22 Critical Sandbox Escapes, Fixed in 3.12.2 — If anything outside your trust boundary can get code into vm2, upgrade to 3.12.2 today and plan to move that code out of process; if vm2 only runs your own code, upgrade on a normal cycle.
What it is
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.
From the GitHub advisory
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
Weakness type: CWE-913.
Product: vm2 (npm) · Assigned by: GitHub_M · Published: 2026-08-17
Affected and fixed versions
| Ecosystem | Package | Vulnerable | First fixed |
|---|---|---|---|
| npm | vm2 | <= 3.11.5 | 3.11.6 |
| Vendor | Product | Affected versions (per CVE record) |
|---|---|---|
| patriksimek | vm2 | < 3.11.6 |
Severity scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_M | 3.1 | 9.8 Critical | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| GitHub | 3.1 | 9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
- Attack vector: network (remotely reachable)
- Attack complexity: low
- Privileges required: none (no login)
- User interaction: none
- Scope: unchanged
CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.
Exploitation and urgency
- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation poc, automatable yes, technical impact total.
- FIRST EPSS (model of 2026-10-21): 0.97% probability of exploitation activity in the next 30 days; percentile 62.
Timeline
- — CVE record published by GitHub_M
- — GitHub-reviewed advisory GHSA-cfcw-xp6x-25gj published (critical)
- — erroneo.us brief: vm2: 22 Critical Sandbox Escapes, Fixed in 3.12.2
- — CVE record last updated
Sources and references
Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.
Vulnerability records
- GitHub Advisory GHSA-cfcw-xp6x-25gj github.com
- CVE.org record CVE-2026-47698 cve.org
- NVD entry CVE-2026-47698 nvd.nist.gov
Other references from the CVE record and advisory
- github.com github.com
- github.com github.com
- github.com github.com