A function or operation returns an incorrect return value or status code that does not indicate the true result of execution, causing the product to modify its behavior based on the incorrect result.
This can lead to unpredictable behavior. If the function is used to make security-critical decisions or provide security-critical information, then the wrong status code can cause the product to assume that an action is safe or correct, even when it is not.
This weakness could place the system in a state that could lead unexpected logic to be executed or other unintended behaviors.
Fuzz testing (fuzzing) is a powerful technique for generating large numbers of diverse inputs - either randomly or algorithmically - and dynamically invoking the code with those inputs. Even with random inputs, it is often capable of generating unexpected results such as crashes, memory corruption, or resource consumption. Fuzzing effectively produces repeatable test cases that clearly indicate bugs, which helps developers to diagnose the issues.
CVE-2003-1132DNS server returns wrong response code for non-existent AAAA record, which effectively says that the domain is inaccessible.
CVE-2001-1509Hardware-specific implementation of system call causes incorrect results from geteuid.
CVE-2001-1559Chain: System call returns wrong value (CWE-393), leading to a resultant NULL dereference (CWE-476).
CVE-2014-1266Chain: incorrect "goto" in Apple SSL product bypasses certificate validation, allowing Adversary-in-the-Middle (AITM) attack (Apple "goto fail" bug). CWE-705 (Incorrect Control Flow Scoping) -> CWE-561 (Dead Code) -> CWE-295 (Improper Certificate Validation) -> CWE-393 (Return of Wrong Status Code) -> CWE-300 (Channel Accessible by Non-Endpoint). The code's whitespace indentation did not reflect the actual control flow (CWE-1114) and did not explicitly delimit the block (CWE-483), which could have made it more difficult for human code auditors to detect the vulnerability.