CVE-2026-92947: vm2 (npm)

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 0.5%, percentile 41: FIRST’s model estimates a 0.5% chance of exploitation activity in the next 30 days, higher than 41% of all scored CVEs (low). 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) <= 3.11.6, fixed in 3.11.7. 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 before 3.11.7 exposes Node's shared Buffer pool to sandboxed code, allowing disclosure of host memory used by Buffer.from, Buffer.concat, and related allocations. Sandboxed code can read and write to host-realm buffers by acquiring ArrayBuffers from small allocations, leading to sensitive data exposure and potential denial-of-service.

From the GitHub advisory

Summary Sandboxed code is able to disclose host memory used by small allocations by Buffer.from, Buffer.concat.

Details vm2 exposes Buffer object to sandboxed code by default. Small Buffer allocations (for example, Buffer.allocUnsafe(), Buffer.from(array), Buffer.from(string), and Buffer.concat()) use the same Buffer pool, which is shared with the sandbox. This allows sandboxed code to disclose host memory used by the functions listed above.

PoC Tested against vm2@3.11.5 in the node REPL.

Impact Since sandbox acquires an ArrayBuffer that is used by the host, it can disclose sensitive data going through functions mentioned above and even write to these buffers, which can lead to sensitive data exposure and potentially denial-of-service.

Weakness type: CWE-200, CWE-653, CWE-668.

Product: vm2 (npm) · Assigned by: VulnCheck · Published: 2026-09-17

Affected and fixed versions

Ecosystem	Package	Vulnerable	First fixed
npm	`vm2`	<= 3.11.6	3.11.7

Vendor	Product	Affected versions (per CVE record)
patriksimek	vm2	< 3.11.7

Severity scores

Scored by	CVSS	Score	Vector
VulnCheck	4.0	10 Critical	`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:L/SC:H/SI:H/SA:L`
VulnCheck	3.1	10 Critical	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:L`
GitHub	3.1	10.0	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:L`

Attack vector: network (remotely reachable)
Attack complexity: low
Attack requirements: none
Privileges required: none (no login)
User interaction: none

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): 0.48% probability of exploitation activity in the next 30 days; percentile 41.

Timeline

2026-08-17 — erroneo.us brief: vm2: 22 Critical Sandbox Escapes, Fixed in 3.12.2
2026-09-17 — CVE record last updated
2026-09-17 — CVE record published by VulnCheck
2026-10-05 — GitHub-reviewed advisory GHSA-fcqc-726x-5wfc published (critical)

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.