Authenticated service interruption via unchecked allocation

NULL pointer dereference in Newlib before 3.3.0 allows remote authenticated users to cause a service interrupt via memory-allocation failure. The __i2b function calls Balloc for a big integer and dereferences the returned pointer without checking for allocation failure, so _x[0] faults when memory is exhausted. The vulnerable path requires an authenticated network caller able to trigger the conversion and a target that reaches allocation failure; the bounded consequence is process or service interruption rather than data disclosure or modification.