The Top 10 OWASP Web Vulnerabilities to Watch for This Year

Wylie Bayes

• 4 min read

For over two decades, the Open Web Application Security Project (OWASP) has been the guiding star for application security. Their flagship release, the OWASP Top 10, represents a broad consensus on the most critical security risks to web applications.

As a penetration tester, this list is your roadmap. As a developer, it's your primary defense checklist. The digital landscape evolves rapidly, and the most recent iterations of the list have shifted focus from isolated coding bugs to broader architectural and systemic failures. Let's break down the current OWASP Top 10 vulnerabilities and how to hunt for them.

1. Broken Access Control

Moving up from the number five spot to claim the crown, Broken Access Control is the most prevalent web vulnerability today. This occurs when users can act outside of their intended permissions.

  • How it manifests: Insecure Direct Object Reference (IDOR) is a classic example. If an application uses an incrementing integer for a user ID (/profile?id=101), simply changing the ID to 102 might grant access to another user's account if the backend doesn't explicitly verify ownership.
  • Pentester tip: Always test multi-tenant applications with at least two user accounts (and one admin account) to verify horizontal and vertical privilege boundaries.

2. Cryptographic Failures

Previously known as "Sensitive Data Exposure," this category focuses specifically on failures related to cryptography, which often lead to data breaches.

  • How it manifests: Transmitting data over unencrypted HTTP, using deprecated hash functions like MD5 or SHA1 for passwords, or failing to salt passwords.
  • Pentester tip: Look for hardcoded cryptographic keys in client-side JavaScript or mobile APKs, and always run SSL/TLS configuration scans on target endpoints.

3. Injection

Injection attacks (SQL, NoSQL, OS Command, LDAP) dropped from the top spot but remain incredibly dangerous. They occur when untrusted user data is sent to an interpreter as part of a command or query.

  • How it manifests: An attacker inputs ' OR 1=1 -- into a login field, altering the backend SQL query to bypass authentication.
  • Pentester tip: Look for input fields that interact with backend databases or underlying operating systems. If an application pings an IP address for you, try appending ; ls -la to test for OS command injection.

4. Insecure Design

This is a relatively new category emphasizing the lack of threat modeling and secure design patterns. A system with a fundamentally insecure design cannot be fixed simply by patching a code implementation bug.

  • How it manifests: Applications that lack rate-limiting on password reset endpoints, or systems that use weak, easily guessable challenge questions for account recovery.
  • Pentester tip: Look for business logic flaws. Can you buy a negative quantity of items in a shopping cart to artificially increase your account balance?

5. Security Misconfiguration

As modern application stacks become more complex (Kubernetes, Docker, Cloud deployments), misconfigurations are incredibly common.

  • How it manifests: Unpatched flaws, default vendor passwords left intact, unprotected AWS S3 buckets, and verbose error messages that leak stack traces and system information.
  • Pentester tip: Brute-force directories for leftover administrative panels (e.g., Tomcat, Jenkins) and check if default credentials like admin/admin or root/root grant access.

6. Vulnerable and Outdated Components

Modern web applications are built on a mountain of third-party open-source libraries. If just one of those libraries has a known CVE, your application is vulnerable.

  • How it manifests: Running a legacy version of jQuery, a vulnerable version of Apache Struts, or Log4j.
  • Pentester tip: Use tools like Wappalyzer or Burp Suite extensions to identify framework versions, and cross-reference them with exploit databases (Exploit-DB, GitHub).

7. Identification and Authentication Failures

When an application incorrectly handles user authentication and session management, attackers can compromise passwords, keys, or session tokens to assume the identities of legitimate users.

  • How it manifests: Permitting automated credential stuffing, allowing weak passwords ("Password123"), or failing to rotate session IDs after a successful login (Session Fixation).
  • Pentester tip: Capture a session cookie, log out, and attempt to use the same cookie to access restricted pages. If it works, session invalidation is broken.

8. Software and Data Integrity Failures

This category relates to code and infrastructure that does not protect against integrity violations. This is directly tied to the rise in software supply chain attacks (like the SolarWinds incident).

  • How it manifests: An application pulling unverified, unsigned updates or relying on plugins/libraries from untrusted sources without validating cryptographic signatures.
  • Pentester tip: Look for CI/CD pipelines that are exposed to the public internet or lack strict access controls.

9. Security Logging and Monitoring Failures

Without logging and monitoring, breaches cannot be detected. Incident response becomes impossible.

  • How it manifests: Auditable events, such as logins, failed logins, and high-value transactions, are not logged, or logs are only stored locally where an attacker can easily delete them.
  • Pentester tip: While difficult to verify from a pure black-box perspective, if you are conducting a collaborative "Purple Team" assessment, check if your malicious actions trigger any alerts for the defensive team.

10. Server-Side Request Forgery (SSRF)

SSRF flaws occur whenever a web application is fetching a remote resource without validating the user-supplied URL. It allows an attacker to force the application to send a crafted request to an unexpected destination, often bypassing firewalls.

  • How it manifests: An application has an "import profile picture from URL" feature. Instead of providing an image URL, the attacker provides http://localhost/admin or the AWS metadata endpoint http://169.254.169.254/latest/meta-data/.
  • Pentester tip: Anytime an application accepts a URL as input, try pointing it back at the application's local loopback address, internal network IPs, or cloud provider metadata services.

Conclusion

The OWASP Top 10 highlights that application security requires a holistic approach. It is no longer just about escaping user input; it requires secure architectural design, strict access controls, and vigilant supply chain management.