Security Digest · Vulnerability record
CVE-2026-26956: VM2 Has a WASM Sandbox Escape
vm2 is an open source vm/sandbox for Node.js.
CVSS 9.8 Critical EPSS 0.9% · p60
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 60: FIRST’s model estimates a 0.9% chance of exploitation activity in the next 30 days, higher than 60% 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 3.10.5. Check your lockfile, including transitive dependencies.
What it is
vm2 is an open source vm/sandbox for Node.js. In version 3.10.4, vm2 is vulnerable to full sandbox escape with arbitrary code execution. Attacker code inside VM.run() obtains host process object and runs host commands with zero host cooperation. This issue has been patched in version 3.10.5.
From the GitHub advisory
Summary
Full sandbox escape with arbitrary code execution. Attacker code inside VM.run() obtains host process object and runs host commands with zero host cooperation.
Details
Confirmed on: vm2 3.10.4, Node.js v25.6.1 (x64 Linux) Trigger: Attacker-controlled code passed to VM.run() Requires: Node.js version with WebAssembly exception handling + JSTag support (tested on v25.6.1)
vm2's sandbox security relies on two JavaScript-level mechanisms: (1) a code transformer that injects handleException() into JS catch clauses to wrap host-realm errors, and (2) bridge Proxies that wrap cross-context objects. Both operate entirely within JavaScript.
Weakness type: CWE-693, CWE-653, CWE-94.
Product: vm2 (npm) · Assigned by: GitHub_M · Published: 2026-05-04
Affected and fixed versions
| Ecosystem | Package | Vulnerable | First fixed |
|---|---|---|---|
| npm | vm2 | <= 3.10.4 | 3.10.5 |
| Vendor | Product | Affected versions (per CVE record) |
|---|---|---|
| patriksimek | vm2 | = 3.10.4 |
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 |
| redhat-SADP | 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): 0.92% probability of exploitation activity in the next 30 days; percentile 60.
Timeline
- — CVE record published by GitHub_M
- — GitHub-reviewed advisory GHSA-ffh4-j6h5-pg66 published (critical)
- — 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-ffh4-j6h5-pg66 github.com
- CVE.org record CVE-2026-26956 cve.org
- NVD entry CVE-2026-26956 nvd.nist.gov
Other references from the CVE record and advisory
- github.com github.com
- github.com github.com
- access.redhat.com access.redhat.com
- RHBZ#2466548 bugzilla.redhat.com
- security.access.redhat.com security.access.redhat.com