CWE-197: Numeric Truncation Error

This example, while not exploitable, shows the possible mangling of values associated with truncation errors:

The above code, when compiled and run on certain systems, returns the following output:

This problem may be exploitable when the truncated value is used as an array index, which can happen implicitly when 64-bit values are used as indexes, as they are truncated to 32 bits.

In the following Java example, the method updateSalesForProduct is part of a business application class that updates the sales information for a particular product. The method receives as arguments the product ID and the integer amount sold. The product ID is used to retrieve the total product count from an inventory object which returns the count as an integer. Before calling the method of the sales object to update the sales count the integer values are converted to The primitive type short since the method requires short type for the method arguments.

However, a numeric truncation error can occur if the integer values are higher than the maximum value allowed for the primitive type short. This can cause unexpected results or loss or corruption of data. In this case the sales database may be corrupted with incorrect data. Explicit casting from a from a larger size primitive type to a smaller size primitive type should be prevented. The following example an if statement is added to validate that the integer values less than the maximum value for the primitive type short before the explicit cast and the call to the sales method.

Note: this is a curated list of examples for users to understand the variety of ways in which this weakness can be introduced. It is not a complete list of all CVEs that are related to this CWE entry.