bourne
Installation:

npm: npm install @hapi/bourne

yarn: yarn add @hapi/bourne

Introduction

Consider this:

> const a = '{"__proto__":{ "b":5}}';
'{"__proto__":{ "b":5}}'

> const b = JSON.parse(a);
{ __proto__: { b: 5 } }

> b.b;
undefined

> const c = Object.assign({}, b);
{}

> c.b
5

The problem is that JSON.parse() retains the __proto__ property as a plain object key. By itself, this is not a security issue. However, as soon as that object is assigned to another or iterated on and values copied, the __proto__ property leaks and becomes the object's prototype.

Bourne.parse(text, [reviver], [options])

Parses a given JSON-formatted text into an object where:

  • text - the JSON text string.
  • reviver - the JSON.parse() optional reviver argument.
  • options - optional configuration object where:
    • protoAction - optional string with one of:
      • 'error' - throw a SyntaxError when a __proto__ key is found. This is the default value.
      • 'remove' - deletes any __proto__ keys from the result object.
      • 'ignore' - skips all validation (same as calling JSON.parse() directly).

Bourne.scan(obj, [options])

Scans a given object for prototype properties where:

  • obj - the object being scanned.
  • options - optional configuration object where:
    • protoAction - optional string with one of:
      • 'error' - throw a SyntaxError when a __proto__ key is found. This is the default value.
      • 'remove' - deletes any __proto__ keys from the input obj.

Changelog

#10
Fix uppercase hex strings validating as safe
#9
Add safeParse()
#8
Change module namespace
#7
Don't assume `hasOwnProperty` is safe
#5
Use syntax available down to Node 4.
#4
Improve regex to only flag keys
#3
Handle escaped unicode characters
#2
Expose validation logic
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