CVE-2026-24118: VM2 Sandbox Breakout Through __lookupGetter__

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 0.9%, percentile 59: FIRST’s model estimates a 0.9% chance of exploitation activity in the next 30 days, higher than 59% 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) <= 3.10.4, 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 version 3.11.0, 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. This issue has been patched in version 3.11.0.

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 lookupGetter method allows to read the getter of an object. It is special in VM2 since it will switch between the host and sandbox version of the method when passed to the other context. This allows to access getters on an object in the host context if the method is called from the host context which can be achieved by using the host apply method which can be accessed through Buffer.apply. Afterwards, this function can be used to call the host version of lookupGetter with Buffer and proto resulting in the prototype lookup method from the host context. With this method the hosts Function.prototype object can be retrieved and the host Function acquired through the constructor property which allows to create and run code in the host context. This issue was attempted to be fixed with https://github.com/patriksimek/vm2/blob/4b009c2d4b1131c01810c1205e641d614c322a29/lib/bridge.js#L427. However, this can be circumvented by using Object.getOwnPropertyDescriptor to get the constructor property.

PoC

Weakness type: CWE-94, CWE-693, CWE-749.

Product: vm2 (npm) · Assigned by: GitHub_M · Published: 2026-05-04

Affected and fixed versions

Severity scores

• 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): 0.91% probability of exploitation activity in the next 30 days; percentile 59.

Timeline

• 2026-05-04 — CVE record published by GitHub_M
• 2026-05-04 — GitHub-reviewed advisory GHSA-grj5-jjm8-h35p published (critical)
• 2026-07-15 — 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

1. GitHub Advisory GHSA-grj5-jjm8-h35p github.com
2. CVE.org record CVE-2026-24118 cve.org
3. NVD entry CVE-2026-24118 nvd.nist.gov

Other references from the CVE record and advisory

1. github.com github.com
2. github.com github.com
3. github.com github.com
4. github.com github.com
5. access.redhat.com access.redhat.com
6. RHBZ#2466502 bugzilla.redhat.com
7. security.access.redhat.com security.access.redhat.com

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