A logic error is a programming mistake in how software makes decisions, applies rules, or checks conditions. The code may be syntactically correct and stable, but it behaves incorrectly because the control flow, validation, or authorization logic is wrong. In security-sensitive components, that can turn a small defect into a serious bypass.
Logic errors matter because attackers often look for places where a system trusts the wrong state, skips a permission check, or accepts an action out of sequence. That can lead to privilege escalation, permission bypass, or other boundary failures. In real defenses, developers and testers hunt for these bugs with code review, threat modeling, and boundary testing, especially in low-level components like firmware, modems, and authentication paths where a single mistaken decision can weaken the whole device.