Vulnerable and outdated components remain a persistent cybersecurity threat across modern software development. As part of the OWASP Top 10, this category (classified as A06:2021) highlights the dangers of using components with known security vulnerabilities or those that are no longer supported. Without proper management, these weak links can be the entry point for serious attacks on your web applications.

Let’s break down what makes this supply-chain security risk so critical—and how to defend against it with an approach that combines proper inventory management with dynamic security testing to focus priority components with real, exploitable vulnerabilities.

What are vulnerable and outdated components?

Vulnerable and outdated components refer to third-party libraries, frameworks, or software dependencies that have known security flaws and/or are no longer maintained. These components often include:

• Open-source libraries
• Backend frameworks
• Client-side JavaScript packages
• Server plugins and middleware

In many cases, third-party components are integrated into applications without ongoing monitoring across the entire software lifecycle, potentially leaving them exposed to exploits long after patches are released.

Examples of vulnerable and outdated components

A common example involves outdated versions of Apache Struts. In 2017, an unpatched vulnerability in Apache Struts was exploited in a major data breach that impacted millions. Despite the availability of updates, many organizations continued using the flawed version, unaware of the risk or unable to update due to compatibility issues.

Other examples include:

• Running a version of Log4j vulnerable to remote code execution (RCE) via Log4Shell
• Using an outdated version of jQuery with known cross-site scripting (XSS) flaws
• Keeping legacy plugins in content management systems like WordPress or Drupal
• Using unpatched database drivers or authentication modules

Apart from having security vulnerabilities, third-party components can also be dangerous in other ways. Read and listen about the Polyfill library crisis where a new project owner started including malicious code in an established package used by thousands of sites.

Why protecting against vulnerable and outdated components matters

There are many valid reasons to continue using an older version of a software library or other component. New versions require testing before and after deployment to make sure they don’t break existing functionality, so sticking with an older version for some time may be a practical necessity. Problems begin when the old version has a known vulnerability that increases your attack surface. 

Risks of using vulnerable and outdated components

Neglecting these components introduces several security and operational risks:

• Known exploitability: Attackers actively scan for versions of popular libraries with known CVEs.
• Automated attacks: Vulnerable components are often targeted by bots, increasing exposure.
• Unauthorized access: An auth bypass vulnerability in an application component could entirely negate access control, exposing sensitive data and allowing escalation.
• Legal and compliance issues: Failing to patch known vulnerabilities may violate compliance standards like PCI DSS or HIPAA.
• Cascading failures: A flaw in a third-party library can affect multiple parts of your application stack.
• Data integrity failures: Component vulnerabilities may enable attackers to introduce malicious code into a component to maintain a persistent presence.

By prioritizing the identification and remediation of these components, organizations can reduce the likelihood of being breached through known attack vectors.

How can you protect against vulnerable and outdated components?

The key to protection is proactive management—knowing what’s in your application, monitoring for vulnerabilities, and acting on verified threats.

Best practices for managing vulnerable and outdated components

1. Inventory all software components: Maintain a complete and updated software bill of materials (SBOM) to track all dependencies.
2. Use tools that verify real risk: Static tools like software composition analysis (SCA) can flag outdated components, but they often flood teams with alerts. A DAST-first approach focuses on what's actually exploitable, helping teams prioritize.
3. Automate updates: Where possible, use dependency management tools to automate updates and security patches.
4. Apply virtual patching: Use web application firewalls (WAFs) as a stop-gap while updates are applied.
5. Integrate security into CI/CD: Embed security checks into the development pipeline to catch issues early.

Securing your applications

Finding and patching every single outdated component isn’t always realistic—but fixing the ones that matter is. That’s why organizations benefit from combining SCA with dynamic application security testing (DAST). While static SCA helps identify outdated components in your code, DAST (and its own dynamic SCA) shows you what components you’re running and whether they have vulnerabilities that are actually exploitable in your live environment.

A DAST-first approach cuts through the noise by validating component vulnerabilities and showing which of them malicious hackers could use. This not only accelerates triage and remediation but also helps security and development teams stay focused on real risk, not false positives or theoretical alerts.

How a DAST-first approach helps manage vulnerable and outdated components

Most organizations rely on static SCA tools to identify outdated or risky components. While static SCA plays a vital role in visibility, it often generates an overwhelming number of alerts—many of which may not be actionable in a real-world context. This creates alert fatigue, delays remediation, and can distract teams from addressing critical issues.

A DAST-first approach flips this model by focusing on actual exploitable vulnerabilities in running applications. Rather than flagging every outdated library present on the server side or your code repository, DAST identifies vulnerable components based on fingerprinting and observed runtime behavior during scanning.

Here’s how a DAST-first strategy adds value:

• Focus on what’s exploitable: DAST evaluates live applications and APIs, identifying components that are actively used, vulnerable, and exploitable, not just out of date.
• Proof-based validation: Tools like Invicti provide automatic proof-of-exploit for common vulnerabilities to confirm that an outdated component poses real risk before escalating it to the development team.
• Faster triage and fewer false positives: Validated findings enable security teams to prioritize the components that need their attention most, accelerating risk reduction and minimizing wasted effort on evaluating non-issues.
• Actionable insights for developers: Developers receive concrete, reproducible details about vulnerabilities in specific components, speeding up decision-making and mitigation.

When used alongside static SCA, a DAST-first approach ensures that you’re not just reacting to aging software but actively securing your applications against the real-world threats those components can introduce. It’s the fastest, most efficient way to reduce risk and protect your application stack from vulnerabilities that matter. And while static SCA only addresses software component security, DAST also covers vulnerabilities in first-party code, APIs, and dynamic dependencies, as well as security misconfigurations and more.

Conclusion

Running vulnerable or outdated components is a constant risk with complex modern software, but they don’t have to be your Achilles’ heel. By knowing what’s in your stack and using security tools that validate real-world risk, you can drastically reduce your exposure.

Combining SBOMs and a robust patch management process with continuous discovery and dynamic security testing through a DAST-first approach is the most effective way to stay secure without slowing down development.

LEARN MORE ABOUT IDENTIFYING VULNERABLE COMPONENTS: Vulnerability Scanner