Security Digest · Vulnerability record
CVE-2026-43997: vm2 Access to Host Object Enables Sandbox Escape
vm2 is an open source vm/sandbox for Node.js.
CVSS 10.0 Critical EPSS 0.8% · p55
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 0.8%, percentile 55: FIRST’s model estimates a 0.8% chance of exploitation activity in the next 30 days, higher than 55% 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) <= 3.10.5, fixed in 3.11.0. Check your lockfile, including transitive dependencies.
What it is
vm2 is an open source vm/sandbox for Node.js. Prior to 3.11.0, it is possible to obtain the host Object. There are various ways to use the host Object, to escape the sandbox, one example would be using HostObject.getOwnPropertySymbols to obtain Symbol(nodejs.util.inspect.custom). This vulnerability is fixed in 3.11.0.
From the GitHub advisory
Summary
It is possible to obtain the host Object, https://github.com/patriksimek/vm2/commit/ebcfe94ad2f864f0bc35e78cff1d921107cfd160 added some protections, but the implementation is incomplete.
Details
There are various ways to use the host Object, to escape the sandbox, one example would be using HostObject.getOwnPropertySymbols to obtain Symbol(nodejs.util.inspect.custom)
PoC
Weakness type: CWE-94, CWE-653.
Product: vm2 (npm) · Assigned by: GitHub_M · Published: 2026-05-13
Affected and fixed versions
| Ecosystem | Package | Vulnerable | First fixed |
|---|---|---|---|
| npm | vm2 | <= 3.10.5 | 3.11.0 |
| Vendor | Product | Affected versions (per CVE record) |
|---|---|---|
| patriksimek | vm2 | < 3.11.0 |
Severity scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_M | 3.1 | 10 Critical | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H |
| redhat-SADP | 3.1 | 10 Critical | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H |
| GitHub | 3.1 | 10.0 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H |
- Attack vector: network (remotely reachable)
- Attack complexity: low
- Privileges required: none (no login)
- User interaction: none
- Scope: changed (can affect other components)
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): 0.77% probability of exploitation activity in the next 30 days; percentile 55.
Timeline
- — GitHub-reviewed advisory GHSA-47x8-96vw-5wg6 published (critical)
- — CVE record published by GitHub_M
- — CVE record last updated
Sources and references
Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.
Vendor and project advisories, patches
- access.redhat.com access.redhat.com
Vulnerability records
- GitHub Advisory GHSA-47x8-96vw-5wg6 github.com
- CVE.org record CVE-2026-43997 cve.org
- NVD entry CVE-2026-43997 nvd.nist.gov
Other references from the CVE record and advisory
- github.com github.com
- access.redhat.com access.redhat.com
- RHBZ#2477203 bugzilla.redhat.com
- security.access.redhat.com security.access.redhat.com
- github.com github.com