How it was found

I would like to report an uninitialized Buffer allocation issue in base64url. It allows to extract sensitive data from uninitialized memory or to cause a DoS by passing in a large number, in setups where typed user input can be passed (e.g. from JSON), on Node.js 4.x and lower.

Module

module name: base64url version: 2.0.0 npm page: https://www.npmjs.com/package/base64url

Module Description

Converting to, and from, base64url

Module Stats

182 924 downloads in the last day 1 097 142 downloads in the last week 4 601 176 downloads in the last month

Vulnerability

Vulnerability Description

The problem arises when a number is passed in, e.g. from user-submitted JSON-encoded data. The API should not propagate the already-bad Buffer issue further.

On Node.js 4.x and below (4.x is still supported), this exposes uninitialized memory, which could contain sensitive data. This can be also used to cause a DoS by consuming the memory when large numbers are passed on input.

Steps To Reproduce:

console.log(require('base64url').encode(1000)) (note uninitialized memory in output) require('base64url').encode(1e8) (note memory usage and time)

Supporting Material/References:

State all technical information about the stack where the vulnerability was found

• Arch Linux Current
• Node.js 4.8.7

Wrap up

• I contacted the maintainer to let them know: Y
• I opened an issue in the related repository: N

I tried to contact the maintainer over email, first time on 2017-03-02, last time on 2018-02-18, but did not receive a reply.

Impact

Sensitive uninitialized memory exposure Denail of Service This issue affects only setups using Node.js 4.x (still supported) or lower.