CWE-1235: Incorrect Use of Autoboxing and Unboxing for Performance Critical Operations

Languages such as Java and C# support automatic conversion through their respective compilers from primitive types into objects of the corresponding wrapper classes, and vice versa. For example, a compiler might convert an int to Integer (called autoboxing) or an Integer to int (called unboxing). This eliminates forcing the programmer to perform these conversions manually, which makes the code cleaner.

However, this feature comes at a cost of performance and can lead to resource exhaustion and impact availability when used with generic collections. Therefore, they should not be used for scientific computing or other performance critical operations. They are only suited to support "impedance mismatch" between reference types and primitives.