What defines weaknesses in software applications that can be exploited by attackers?

The correct choice is security vulnerabilities. These are specific flaws or weaknesses found in software applications that can be exploited by attackers to gain unauthorized access or perform harmful actions. Vulnerabilities can arise from various sources including coding errors, misconfigurations, or inadequate security practices.

Understanding security vulnerabilities is crucial because they are the focal points for potential attacks. By identifying and addressing these vulnerabilities, organizations can enhance their overall security posture and reduce the risk of breaches.

Other options serve different functions in the realm of security. Security policies establish guidelines and protocols for protecting information, but they do not directly define weaknesses. Access controls are mechanisms that restrict access to systems and data based on user permissions, and while they help mitigate risks, they do not define vulnerabilities themselves. Service downtime refers to periods when a service is unavailable, which can be a consequence of an exploitation incident but does not directly relate to the definition of weaknesses in software applications.