CWE-768

Incorrect Short Circuit Evaluation
AI Translation Available

The product contains a conditional statement with multiple logical expressions in which one of the non-leading expressions may produce side effects. This may lead to an unexpected state in the program after the execution of the conditional, because short-circuiting logic may prevent the side effects from occurring.

Status
incomplete
Abstraction
variant
Likelihood
low
C Not Language-Specific

Usage of short circuit evaluation, though well-defined in the C standard, may alter control flow in a way that introduces logic errors that are difficult to detect, possibly causing errors later during the product's execution. If an attacker can discover such an inconsistency, it may be exploitable to gain arbitrary control over a system.

If the first condition of an 'or' statement is assumed to be true under normal circumstances, or if the first condition of an 'and' statement is assumed to be false, then any subsequent conditional may contain its own logic errors that are not detected during code review or testing.

Finally, the usage of short circuit evaluation may decrease the maintainability of the code.

Common Consequences

confidentiality integrity availability
Impacts
varies by context

Detection Methods

automated static analysis

Potential Mitigations

Phases:
implementation
Descriptions:
• Minimizing the number of statements in a conditional that produce side effects will help to prevent the likelihood of short circuit evaluation to alter control flow in an unexpected way.