It was reported that Python built-in _json module have a flaw (insufficient bounds checking), which allows a local user to read current process' arbitrary memory.
Quoting the upstream bug report:
The sole prerequisites of this attack are that the attacker is able to control or influence the two parameters of the default scanstring function: the string to be decoded and the index.
The bug is caused by allowing the user to supply a negative index value. The index value is then used directly as an index to an array in the C code; internally the address of the array and its index are added to each other in order to yield the address of the value that is desired. However, by supplying a negative index value and adding this to the address of the array, the processor's register value wraps around and the calculated value will point to a position in memory which isn't within the bounds of the supplied string, causing the function to access other parts of the process memory.