CWE-252Unchecked Return Value

Description

The product does not check the return value from a method or function, which can prevent it from detecting unexpected states and conditions.

Two common programmer assumptions are "this function call can never fail" and "it doesn't matter if this function call fails". If an attacker can force the function to fail or otherwise return a value that is not expected, then the subsequent program logic could lead to a vulnerability, because the product is not in a state that the programmer assumes. For example, if the program calls a function to drop privileges but does not check the return code to ensure that privileges were successfully dropped, then the program will continue to operate with the higher privileges.

Common consequences

• Availability,Integrity→Unexpected State,DoS: Crash, Exit, or Restart
  An unexpected return value could place the system in a state that could lead to a crash or other unintended behaviors.

Potential mitigations

• Implementation
  Check the results of all functions that return a value and verify that the value is expected.
• Implementation
  For any pointers that could have been modified or provided from a function that can return NULL, check the pointer for NULL before use. When working with a multithreaded or otherwise asynchronous environment, ensure that proper locking APIs are used to lock before the check, and unlock when it has finished [REF-1484].
• Implementation
  Ensure that you account for all possible return values from the function.
• Implementation
  When designing a function, make sure you return a value or throw an exception in case of an error.

Related CWEs

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