Pen Testing: 5 Most Common Vulnerabilities Found in Real-World Assessments

Penetration testing (pen testing) is a tried and true, proactive way to discover and remediate security weaknesses and blind spots in your IT environment, and more importantly, build resilience against the adversaries who attempt to exploit them.

Pen testing has always been a non-negotiable component of standard offensive security strategies, but it has become more critical than ever. In fact, according to the NIST National Vulnerability Database (NVD), over 6,800 new vulnerabilities have been published in just the first six weeks of 2026, with an average of 150+ vulnerabilities identified every day.¹

Having conducted over 30,000 pen testing engagements, BreachLock’s security experts have analyzed extensive data on how these vulnerabilities manifest across a diverse array of IT environments. This blog will deliver a clear overview of the top 5 most common vulnerabilities that repeatedly appear in our real-world assessments.

1. Injection Flaws

An injection flaw refers to incorrect or malicious input that a threat actor may provide to an application, causing the application to behave in unexpected, incorrect, or harmful ways.

Potential Consequences

In the presence of an injection flaw, the application’s interpreter – browser, database, command line, etc. – executes malicious input as commands. This may allow adversaries to gain unauthorized access to the application, disrupt services, or steal business-critical data.

Recommended Fixes

There are many ways to root out injection vulnerabilities and minimize the probability of injection attacks:

• Use positive server-side input validation
• Sanitize user inputs when using dynamic SQL within stored procedures
• Use prepared statements with parameterized queries
• Escape special characters using the interpreter’s specific syntax for residual dynamic queries

2. Broken Authentication

Authentication issues may be the result of weak passwords or missing multifactor authentication (MFA). Another cause is flawed session handling procedures: it may not correctly invalidate user sessions or authentication tokens during logout or a period of inactivity, or the session identifiers may be exposed in the URL.

Potential Consequences

Authentication flaws could trick a system into recognizing an invalid, incorrect, or malicious user as legitimate. This may allow threat actors to execute account takeovers, brute force attacks, or automated attacks such as credential stuffing. Malicious users could also create new accounts with already known breached credentials to gain unauthorized access to a system and its data.

Recommended Fixes

These controls can help organizations address authentication vulnerabilities and prevent cyberattacks:

• Implement MFA, particularly for sensitive and/or business-critical systems
• Use password managers to securely generate and store passwords
• Validate new accounts and password changes against lists of known breached credentials
• Use a secure session manager that generates new random session IDs after every login

3. Security Misconfigurations

Incorrect setup of systems, applications, or cloud services could create security gaps that open the door to breaches. One common configuration error is to enable or install unnecessary ports, accounts, permissions, or privileges. Another is to disable (or not enable) the latest security features. Insecure values of security settings within application servers, libraries, and databases also create vulnerabilities, as do the use of weak encryption protocols or expired certificates on production systems.

Potential Consequences:

Security misconfigurations may allow threat actors to break into enterprise systems and exfiltrate sensitive information. These errors also increase the ransomware attacks, system disruptions, and Advanced Persistent Threat (APT) breaches.

Recommended Fixes:

following The measures could minimize security misconfigurations and reduce attack risk:
Regularly review and update the configurations of all security notes, updates, and patches

• Use different credentials for development, QA, and production environments
• Change default passwords, particularly for admin users
• Implement automations to continuously verify all configurations and settings
• Implement role-based access control (RBAC) to restrict access to a limited group of authorized users

4. Outdated Software

Software – web applications, operating systems, browsers, development frameworks, database management systems (DBMS), APIs, libraries, and more – is said to be outdated when its vendor fails to patch it with the latest security updates. Software can also become outdated when it is no longer supported (end-of-life) by its developer.

Potential Consequences:

Outdated or unpatched software may contain vulnerabilities that provide an entry point for malware, ransomware, and data breaches. It may also put organizations at risk of remote code execution (RCE), denial of service (DoS), and cross-site scripting (XSS) injection attacks.

Recommended Fixes:

Adopting these security practices can help to keep software up-to-date and secure:

• Maintain an asset register to keep track of all installed software and curtail the growth of potentially risky “shadow IT.”
• Implement an automated patch management process to minimize manual patching effort and eliminate errors.
• Regularly scan for software vulnerabilities with an automated vulnerability scanner and assess discovered vulnerabilities by comparing against public sources like the NIST’s NVD.
• Only use software from trusted vendors.

5. Insufficient Logging and Monitoring

Logging and alerting may be insufficient when auditable events (e.g., failed login attempts) are not logged, when log messages are not generated, or when applications are not continuously monitored for suspicious activities. This can affect visibility into the organization’s security posture and attack surface.

Potential Consequences:

Missing or inconsistently available security logs hinder security teams from detecting active, real-time attacks and breaches. Alerting failures can slow down incident response and prolong system downtime, resulting in revenue losses and reputational damage for the organization.

Recommended Fixes:

• Use application code, network firewalls, and database applications as event data sources to generate log entries
• Implement a log management solution that centralizes and analyzes all log data from networks, servers, and applications
• Deploy an observability tool that provides real-time insights for proactive incident investigation and remediation
• Add honeytokens into critical applications to trigger alerts following unauthorized access

Proactively Remediate Vulnerabilities with BreachLock Pen Testing

Proactively identifying vulnerabilities, including the five highlighted in this blog, is only the first step in a proactive offensive security strategy. To effectively reduce risk, organizations need comprehensive, scalable, expert-led pen testing that goes beyond automated vulnerability scanning.

Having conducted over 30,000 pen testing engagements, BreachLock delivers Penetration Testing as a Service(PTaaS) to help organizations discover, prioritize, and remediate vulnerabilities faster. By leveraging a 100% in-house, CREST-certified, expert team of penetration testers accelerated by AI-powered automation, BreachLock provides the evidence-backed insights and proof-of-concepts (PoCs) needed to prioritize and close critical security gaps faster.

The BreachLock PTaaS model, delivered through the BreachLock Unified Platform for an easy-to-manage scoping, scheduling, and results delivery process, offers several key benefits to streamline the testing process:

• Real-Time Results: You can track the status of pen test engagements and view most vulnerability findings in real-time through a centralized platform, minimizing the window between vulnerability identification and remediation.
• Flexible & On-Demand Testing: BreachLock enables you to run pentests on your schedule, whether it’s one-time, continuous, or periodic. Scheduling and adjusting the scope of your pen test projects is as simple as just a few clicks in the BreachLock Unified Platform.
• Re-Testing Included with Every Engagement: Ensuring that patches you implement are effective as you remediate easily with unlimited automated re-testing on most findings. When you’re finished remediating, we include a free manual re-test to validate that your patches are effective and that your security posture has improved with an updated report.
• Seamless Integration: Foster collaboration between your security and development teams with direct DevOps and ticketing integrations, including Jira, Slack, Trello, Okta, ServiceNow, GitHub, and more.
• Compliant Reporting: Download audit-ready reports designed for both technical teams and executive leadership directly from the BreachLock Unified Platform. Our reports align with industry compliance standards requirements, including SOC 2, GDPR, PCI DSS, HIPAA, ISO 27001, and more.

To learn more about how BreachLock can help you accelerate your pen testing cycles by 50% while lowering the total cost of ownership (TCO), contact us today to schedule a free, consultative discovery call with an expert.

About BreachLock

BreachLock is a global leader in offensive security, delivering scalable and continuous security testing. Trusted by global enterprises, BreachLock provides human-led and AI-powered Attack Surface Management, Penetration Testing as a Service (PTaaS), Red Teaming, and Adversarial Exposure Validation(AEV) solutions that help security teams stay ahead of adversaries.

With a mission to make proactive security the new standard, BreachLock is shaping the future of cybersecurity through automation, data-driven intelligence, and expert-driven execution.

References

1. NIST (2025). NVD Dashboard. https://nvd.nist.gov/general/nvd-dashboard

Author

BreachLock Labs