Broken Access Control: Why It Tops Both OWASP and Inspectiv’s Bug Bounty Reports

Every year, the OWASP Top Ten highlights the most critical security risks facing web applications. Until the late 2025 update from OWASP, the #1 category remains Broken Access Control and Inspectiv’s own bug bounty data tells the same story. Across our bug bounty programs, vulnerabilities tied to improper access control are the most frequently reported issue by security researchers comprising 38% of our vulnerabilities.

This alignment between OWASP’s global findings and Inspectiv’s platform data underscores a simple truth: access control is hard, even for experienced teams. Modern development practices including continuous deployment, distributed architectures, and fast-moving product cycles make it easier than ever to introduce subtle authorization flaws.

In this article, we’ll unpack why broken access control is so pervasive, how organizations can detect it before attackers do, and what steps lead to long-term, resilient remediation.

Why Authorization Fails So Often

At its core, access control determines who can do what within an application. It enforces the boundaries between user roles, data sets, and system functions. When these boundaries fail, attackers can act outside their permissions viewing other users’ data, modifying records, or escalating privileges.

Inspectiv’s vulnerability data shows that these flaws appear across every industry and tech stack. Why? Because access control is tightly tied to each app’s unique business logic. Unlike SQLi or XSS, there’s no universal pattern to catch. Every product defines “who should have access” differently, so every implementation becomes a custom solution and therefore a potential source of bugs.

Three realities amplify the problem:

• Rapid Development and Deployment - Teams ship new features daily or even hourly. In this fast-moving cycle, access rules are often added piecemeal: a quick conditional here, an API flag there instead of being enforced consistently across the application.
• Decentralized Architectures - Modern systems rely on many APIs, microservices, and cloud functions. Each may handle authorization differently, and inconsistency accumulates over time. A missing check in one service can undermine the entire system’s security.
• Assumed Trust Between Internal Services - Internal APIs often trust traffic too much. Without strict authentication and authorization between services, one compromised component can lead to total exposure.

What Happens When Access Rules Fail

A few anonymized examples from Inspectiv’s bug bounty programs illustrate how these vulnerabilities manifest:

• Insecure Direct Object Reference (IDOR): A SaaS platform allows users to access documents by changing an object ID in a URL. Researchers could view other customers’ invoices by incrementing the ID number.
• Privilege Escalation: A dashboard didn’t verify user roles on the backend, so attackers could access privileged API endpoints even though the UI hid those options.
• Cross-Tenant Data Manipulation: In a multi-tenant environment, the backend API failed to validate tenant boundaries, letting one customer access or modify another tenant’s customer data.

Each represents a unique breakdown in authorization logic not a technical exploit, but a design oversight.

Detecting and Preventing Authorization Flaws

Preventing these issues requires visibility and consistent testing. Based on Inspectiv’s experience running large-scale vulnerability programs, the best approach combines several layers:

• Architecture Review - Start by mapping out your system’s access model: roles, privileges, and data boundaries. Identify where permissions are enforced and where they aren’t. This exercise alone often reveals hidden risks.
• Continuous Bug Bounty Testing - Automated scanners can’t simulate human creativity. That’s where Inspectiv’s platform excels connecting your environment with skilled researchers who probe for logic and authorization flaws 24/7.
• Periodic Penetration Tests - Structured penetration tests dig deeper into workflows and validate that past issues are resolved. They also catch new risks after major releases or architecture changes.
• Automated Guardrails - Use static analysis and automated permission checks to detect missing authorization logic early in development. Automation won’t catch everything, but it strengthens your baseline.

Together, these layers create a continuous feedback loop between your developers and the security community ensuring you find issues before attackers do.

Remediation: Design Security In, Don't Patch It On 

When a broken access control vulnerability is reported, the instinct is to “patch the hole.” But quick fixes rarely address the deeper cause of inconsistent or decentralized authorization logic.
The more sustainable solution is to redesign your access model with security at its core:

• Centralize authorization logic instead of scattering checks throughout code.
• Default to deny and only grant access explicitly.
• Apply consistent enforcement across all services and APIs.
• Adopt scalable models like role-based (RBAC) or attribute-based access control (ABAC).
• Review all security-sensitive code changes with peer oversight.

This approach takes more upfront effort, but it pays dividends. Teams that re-architect access control systems save time and resources in the long run by eliminating recurring vulnerabilities and reducing reliance on reactive fixes.

The Inspectiv Takeaway 

Broken Access Control remains the most common vulnerability because it’s the most human embedded in custom business logic, rushed deployments, and evolving architectures. Our bug bounty data confirms what OWASP has long warned: authorization is one of the hardest things to get right.

But it’s also one of the most preventable. With continuous testing, clear visibility into architecture, and a commitment to secure design, organizations can break the cycle of recurring access control bugs.

At Inspectiv, we help security and engineering teams operationalize this mindset. Our platform connects customers with expert researchers who test what automation can’t providing actionable findings, real-time insight, and validation that your controls work as intended. Book a demo to see how continuous security testing can help you eliminate critical vulnerabilities before they reach production.

Access control may be complex, but securing it doesn’t have to be chaotic. With the right visibility and testing cadence, you can move fast and stay secure.