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CVE-2026-93603

vm2 before 3.12.1 Sandbox Escape RCE via Non-Strict Host Function

CVSS 4.0 10.0 CRITICALCVSS 3.1 10.0 CRITICALCheck source for fixed versionsKEV status unknown

Original advisory

cve-program · CVE-2026-93603

Published

vm2 through 3.12.0 (fixed in 3.12.1) does not correctly handle a nullish `this` receiver in the apply trap of its bridge (lib/bridge.js): when sandboxed code calls a host-provided non-strict (sloppy-mode) function without a receiver — e.g. `fn()`, a detached method, `fn.call()`, `fn.apply(undefined)`, `Reflect.apply(fn, undefined, [])`, or `fn.bind()()` — the undefined receiver is passed straight through to the host call, and V8 substitutes the host realm's global object for `this`. vm2 then wraps and returns that object to the sandbox, giving sandboxed script a live proxy of the host global. This allows a complete sandbox escape: untrusted script can reach `process` and execute arbitrary code/commands on the host (for example via `process.getBuiltinModule('child_process').execSync`). Exploitation requires that the embedding application expose at least one non-strict host function to the sandbox; strict-mode and ES module host functions are not affected.

Read the publisher's advisory

Affected versions, risk and source history

cve-program · CVE-2026-93603

Published

vm2

Vendor product

Publisher's version information

Shown as published. These rules are not interpreted as NuGet package version ranges.

{
                    "vendor": "patriksimek",
                    "product": "vm2",
                    "defaultStatus": "unaffected",
                    "packageURL": "pkg:npm/vm2",
                    "versions": [
                        {
                            "version": "0",
                            "status": "affected",
                            "versionType": "semver",
                            "lessThan": "3.12.1"
                        },
                        {
                            "version": "3.12.1",
                            "status": "unaffected",
                            "versionType": "semver"
                        }
                    ]
                }

Original source record · Cite this exact observation · Complete original publisher JSON