The 10 Most Common API Security Mistakes and How To Solve Them

An Application Programming Interface (API) can be defined as a set of protocols, routines, and tools that developers use to build software applications. It specifies how software components should interact with each other and enables communication between different software applications, allowing them to exchange data and functionality. APIs provide a standardized interface for developers that allows them to access the various functionalities of applications over the internet. With this, developers can build software applications that can leverage the functionality of other software components without needing to know the underlying implementation details. 

As more data is being exposed via API calls and more sensitive information is being exchanged per second using APIs, API security should be at the forefront of developers, cyber security professionals, and management personnel. A recent survey spanning the past 12 months sighted that 94% had some security issue with their production APIs over the past year, with vulnerabilities topping the list at 41%, followed closely by authentication problems at 40%; 31% had also experienced a sensitive data exposure or privacy incident, and 17% had experienced a security breach. 

API Security

API security is an important aspect of building and using APIs, as it ensures that sensitive data and resources are protected from unauthorized access and malicious attacks. While traditional web prevention mechanisms like Captcha and browser fingerprinting do not work for APIs because of the volume of accesses needed by even a single user, following the OWASP API Security Top 10 list is a great place to start with API security. This ensures that your APIs are best protected against the top 10 API security vulnerabilities.

Other API best practices to adopt outside the OWASP Security API list include encryption, OAuth2, authentication, firewalls, data validation, using an API gateway management software, and setting throttling limits and quotas. These best practices, when followed, ensure APIs remain as safe as possible while retaining a high level of functionality.

However, when not adopted properly, these best practices can be detrimental to API security inevitably leading to data usage and misuse. Here are 10 common API security mistakes and how to avoid them:

Insufficient authentication and authorization: This is one of the most common API security mistakes. Insufficient authentication and authorization can occur when an API allows users to access sensitive data or perform actions without properly verifying their identity and ensuring that they have the necessary permissions to perform the action. This leads to unauthorized access to sensitive data and resources. 

Solution: To avoid this mistake, implement strong authentication and authorization mechanisms that verify the identity of the user and limit access to resources based on their level of authorization. OAuth2 is a good solution to cater to proper authentication and authorization. 

Poor input validation: Poor input validation can lead to injection attacks, where attackers inject malicious code into the API. Poor input validation occurs when an API fails to properly validate user input, allowing attackers to inject malicious code into the API and execute it.

Solution: To avoid this mistake, implement input validation mechanisms that check for data type, length, and format, and sanitize all user input before processing it.

Lack of encryption: API data should always be encrypted to protect it from unauthorized access. When an API transmits or stores data in an unencrypted format, it can be intercepted or accessed by attackers, putting the data at risk. Attackers can intercept unencrypted data using a variety of techniques, including sniffing network traffic or intercepting data stored on the server or client.

Solution: To avoid this mistake, use encryption mechanisms such as SSL/TLS to encrypt all data in transit and implement encryption mechanisms such as AES or RSA to encrypt data at rest.

Exposure of sensitive data: Sensitive data such as passwords, API keys, and user credentials should never be exposed to the public. 

Solution: To avoid this mistake, use encryption and hashing mechanisms to store sensitive data, and never expose them in API responses or logs.

Inadequate rate limiting: Rate limiting is the process of limiting the number of API requests that can be made by a user or IP address within a certain period. Inadequate rate limiting can lead to denial of service (DoS) attacks, where attackers flood the API with requests to overload the system. 

Solution: To avoid this mistake, implement rate-limiting mechanisms that limit the number of requests that can be made to the API within a specific time.

Lack of logging and monitoring: Logging and monitoring are essential security practices that provide visibility into an API's activities, allowing developers and security professionals to detect and investigate potential security threats. Logging involves recording events and actions within the API, such as user authentication attempts, API requests and responses, and system errors.

Solution: Implement logging and monitoring mechanisms that capture all API requests and responses and alert administrators to suspicious activity.

Improper error handling: Error handling refers to the process of managing errors and exceptions that occur within an API. Improper error handling can allow attackers to exploit vulnerabilities and obtain sensitive information about the API's functionality, its users, and its underlying system.

Solution: To avoid this mistake, implement proper error handling mechanisms that provide minimal information to users and log detailed error information for administrators.

Vulnerable third-party libraries: Third-party libraries used in the development of the API may contain vulnerabilities that attackers can exploit.

Solution: To avoid this mistake, keep all third-party libraries up-to-date with the latest security patches and perform regular vulnerability scans.

Lack of testing: Lack of testing can lead to undetected security vulnerabilities and weaknesses. Testing is an essential part of the software development lifecycle and is critical to identifying and addressing potential security threats within an API.

Solution: It is important to perform thorough API testing using security tools and techniques such as penetration testing and vulnerability scanning.

Lack of security policies and procedures: Lack of security policies and procedures is a common API security mistake that can lead to inconsistent and ineffective security practices. Security policies and procedures are essential for establishing consistent security practices within an organization and ensuring that security risks are properly managed.

Solution: Organizations should implement security policies and procedures that outline best practices for API security and ensure that all developers and administrators are trained in these practices.

Lack of runtime security: Sometimes organizations focus on the pre-production aspects like scanning and vulnerability analysis and forget the importance of watching APIs in production. Most API attacks are business logic attacks, so you need to watch whether APIs are being abused or manipulated.

Solution: Organizations should implement dedicated API security protection in runtime that has the ability to baseline typical behavior and identify anomalies, and more importantly, attacks so companies can block attackers before they can steal data or access accounts. 

By avoiding these common API security mistakes and implementing best practices for API security, you can help ensure that your APIs are secure and protected from unauthorized access and malicious attacks.


In conclusion, APIs offer a standardized interface for developers to access application functionalities over the Internet. With the increasing exchange of sensitive information through APIs, properly implementing strong authentication and authorization mechanisms, proper input validation, encryption, rate limiting, logging and monitoring, proper error handling, keeping third-party libraries up-to-date, performing thorough testing, and establishing security policies and procedures are essential steps to ensure API security. Failure to implement these practices can lead to vulnerabilities that attackers can exploit, potentially leading to data breaches and other security incidents. By taking these steps, organizations can reduce the risk of security incidents and protect their valuable data and resources. 

About Author:

Musa is a certified Cybersecurity Analyst and Technical writer. He has experience working as a Security Operations Center (SOC) Analyst and Cyber Threat Intelligence Analyst (CTI) with a history of writing relevant cybersecurity content for organizations and spreading best security practices. He is a regular writer at Bora

His other interests are Aviation, History, DevOps with Web3 and DevSecOps. In his free time, he enjoys burying himself in a book, watching anime, aviation documentaries and sports, and playing video games.