Uninititialized Memory Exposure Affecting njwt package, versions <1.0.0
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Test your applications- Snyk ID npm:njwt:20180614
- published 24 Jun 2018
- disclosed 14 Jun 2018
- credit ChALkeR
How to fix?
There is no fix version for njwt.
Overview
njwt is the cleanest JSON Web Token (JWT) library for Node.js developers..
Affected versions of this package are vulnerable to Uninitialized Memory Exposure. A malicious user could 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.
Note Uninitialized Memory Exposure impacts only Node.js 6.x or lower, Denial of Service impacts any Node.js version.
Details
The Buffer class on Node.js is a mutable array of binary data, and can be initialized with a string, array or number.
const buf1 = new Buffer([1,2,3]);
// creates a buffer containing [01, 02, 03]
const buf2 = new Buffer('test');
// creates a buffer containing ASCII bytes [74, 65, 73, 74]
const buf3 = new Buffer(10);
// creates a buffer of length 10
The first two variants simply create a binary representation of the value it received. The last one, however, pre-allocates a buffer of the specified size, making it a useful buffer, especially when reading data from a stream.
When using the number constructor of Buffer, it will allocate the memory, but will not fill it with zeros. Instead, the allocated buffer will hold whatever was in memory at the time. If the buffer is not zeroed by using buf.fill(0), it may leak sensitive information like keys, source code, and system info.