When it comes to web app security, there are several key threats that developers and security professionals should be diligent about: 1. SQL Injection: SQL injection attacks occur when an attacker inserts malicious SQL code into input fields, potentially gaining unauthorized access to the database. 2. Cross-Site Scripting (XSS): XSS attacks involve injecting malicious scripts into web pages viewed by other users, compromising their data. 3. Cross-Site Request Forgery (CSRF): CSRF attacks trick users into unintentionally performing actions on a website that they are authenticated to, leading to unauthorized transactions. 4. Clickjacking: Clickjacking involves tricking a user into clicking on something different from what they perceive, potentially leading to unintended actions. 5. Denial of Service (DoS) attacks: DoS attacks overwhelm a web server with illegitimate traffic, causing it to become unresponsive to legitimate users. To mitigate these threats, developers should implement security best practices such as input validation, parameterized queries, and secure coding practices. Regular security assessments and penetration testing can also help identify vulnerabilities