Affected versions of the package are vulnerable due to the unsafe use of the Buffer() method. Uninitialized memory may be exposed when a value of type number is provided to various methods in mysql which require allocation of buffers and results in concatenation of uninitialized memory to the buffer collection.
This vulnerability is unlikely to be exploited, but may be possible if a server-side mysql accepts typed input for passwords from the client even though the user doesn’t control the server-side code (i.e through JSON format).
Constructing a Buffer class with integer N creates a Buffer of length N with raw (not "zero-ed") memory.
In the following example, the first call would allocate 100 bytes of memory, while the second example will allocate the memory needed for the string "100":
// uninitialized Buffer of length 100
x = new Buffer(100);
// initialized Buffer with value of '100'
x = new Buffer('100');
You can read more about the insecure Buffer behavior on our blog.