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https://github.com/hacksparrow/safe-eval

Safer version of eval()
https://github.com/hacksparrow/safe-eval

Last synced: 4 months ago
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Safer version of eval()

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# safe-eval [![npm version](https://badge.fury.io/js/safe-eval.svg)](https://badge.fury.io/js/safe-eval) [![Build Status](https://travis-ci.org/hacksparrow/safe-eval.svg?branch=master)](https://travis-ci.org/hacksparrow/safe-eval)



**NOTE**



`safe-eval` `0.3.0` and below are affected by a sandbox breakout vulnerability - [NSP 337](https://nodesecurity.io/advisories/337), [CVE-2017-16088](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-16088).



Version `0.4.0` fixes this vulnerability. It is highly recommended to upgrade to the latest version if you are using `safe-eval` for executing code not generated by yourself. Thanks [@kauegimenes](https://github.com/kauegimenes) for the patch.



_UPDATE 27/08/2018:_ There are still ways to crash the Node process, please use `safe-eval` only with content created by yourself or from trusted sources. User-submitted data should not be run through `safe-eval`. Thanks [@cpcallen](https://github.com/cpcallen) for the report.



## What is this?



`safe-eval` lets you execute JavaScript code without having to use the much discouraged and feared upon `eval()`. `safe-eval` has access to all the standard APIs of the [V8 JavaScript Engine](https://code.google.com/p/v8/). By default, it does not have access to the Node.js API, but can be given access using a context object. It is implemented using [node's vm module](https://nodejs.org/api/vm.html).



Currently, it works only with Node.js, and the JavaScript code must be an expression (something which evaluates to a value).



## Installation



```sh

npm install safe-eval --save

```



## Usage



```js

var safeEval = require('safe-eval')

```



**safeEval(code, [context], [options])**



`code` is the JavaScript code you want to execute.



`context` is an object of methods and properties, these methods and properties are interpreted as global objects in `code`. Be careful about the objects you are passing to the context API, because they can completely defeat the purpose of `safe-eval`.



`options` is the [options object](https://nodejs.org/api/vm.html) for the vm executing the code.



### Examples



```js

// string concatenation

var code = '"app" + "le"'

var evaluated = safeEval(code) // "apple"

```



```js

// math

var code = 'Math.floor(22/7)'

var evaluated = safeEval(code) // 3.142857142857143

```



```js

// JSON

var code = '{name: "Borat", hobbies: ["disco dance", "sunbathing"]}'

var evaluated = safeEval(code) // {name: "Borat", hobbies: ["disco dance", "sunbathing"]}

```



```js

// function expression

var code = '(function square(b) { return b * b; })(5)'

var evaluated = safeEval(code) // 25

```



```js

// no access to Node.js objects

var code = 'process'

safeEval(code) // THROWS!

```



```js

// your own context API - access to Node's process object and a custom function

var code = '{pid: process.pid, apple: a()}'

var context = {

  process: process,

  a: function () { return 'APPLE' }

}

var evaluated = safeEval(code, context) // { pid: 16987, apple: 'APPLE' }

```



```js

// pass an options object to the vm

var code = 'process'

safeEval(code, {}, { filename: 'myfile.js'}) // myfile.js can be seen in the stacktrace

```



## License (MIT)



Copyright (c) 2016 Hage Yaapa



Permission is hereby granted, free of charge, to any person obtaining a copy

of this software and associated documentation files (the "Software"), to deal

in the Software without restriction, including without limitation the rights

to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

copies of the Software, and to permit persons to whom the Software is

furnished to do so, subject to the following conditions:



The above copyright notice and this permission notice shall be included in all

copies or substantial portions of the Software.



THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE

AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE

SOFTWARE.