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fix: reject __proto__/constructor/prototype filter keys (prototype pollution) #172

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fix: reject __proto__/constructor/prototype filter keys (prototype pollution) #172

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9 changes: 9 additions & 0 deletions src/index.js
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Original file line number Diff line number Diff line change
@@ -1,5 +1,9 @@


// Query-string keys that must never be used as an object key, because writing
// through them mutates Object.prototype for the whole process.
const FORBIDDEN_KEYS = ['__proto__', 'constructor', 'prototype'];

const builtInCasters = {
boolean: (val) => val === 'true',
date: (val) => new Date(val),
Expand Down Expand Up @@ -214,6 +218,11 @@ const getFilter = (filter, params, options) => {
})
.filter(
({ key }) =>
// Keys that would walk into Object.prototype are always rejected:
// `result['__proto__'][op] = value` writes onto the prototype of every
// object in the process (prototype pollution), and neither name is a
// usable Mongo field anyway.
!FORBIDDEN_KEYS.includes(key) &&
!options.blacklist.includes(key) &&
(!options.whitelist || options.whitelist.includes(key))
)
Expand Down