Your Guide to OWASP Top 10 Vulnerabilities
Understand the 2026 OWASP Top 10 vulnerabilities. Our expert guide details each risk with examples and actionable steps to secure your applications.
Your Guide to OWASP Top 10 Vulnerabilities
Understand the 2026 OWASP Top 10 vulnerabilities. Our expert guide details each risk with examples and actionable steps to secure your applications.
Valiant Team
7/4/202612 min read
1. A01 Broken Access Control
Broken access control isn't subtle. A user changes /user/profile?id=123 to /user/profile?id=124 and sees another customer's records. An employee edits a JWT claim from user to admin and reaches administrative functions. An API accepts a delete request without checking ownership, and one tenant can remove another tenant's data.
OWASP's 2021 list puts Broken Access Control at the top, and Sucuri notes that 94% of tested applications contained this weakness in that edition of the list in its OWASP Top 10 2021 breakdown. That aligns with what offensive testers see constantly. Scanners miss the business logic. Humans find it.
Why executives should care
Access control failures turn a minor bug into a major breach. If a normal user can read payroll data, change account settings, or access an admin panel, the issue becomes legal, financial, and operational fast. In multi-tenant SaaS, this is often the difference between an isolated flaw and a customer-notification event.
What works is disciplined server-side enforcement. What doesn't work is trusting the client, relying on hidden buttons, or assuming a role claim in a token is enough.
Enforce authorization server-side: Check every function and API endpoint, every time.
Standardize policy models: Use RBAC or ABAC frameworks that developers can't bypass casually.
Test tenant boundaries: A strong web application or API penetration test should attempt cross-user and cross-tenant abuse.
Clean up privilege creep: Review orphaned accounts, stale roles, and service permissions regularly.
Practical rule: If authorization isn't enforced in middleware or central policy logic, teams will implement it inconsistently.
Valiant Cyber Solutions typically uncovers this category through web application penetration testing and API security testing, especially when workflows involve role changes, object references, and tenant scoping.
2. A02 Cryptographic Failures
Cryptographic failures usually start with an ordinary business decision. A team stores sensitive exports for convenience. A legacy login stack still uses old password hashing. An internal app skips transport encryption because it's "only for staff." Those shortcuts age badly.
Indusface notes that Cryptographic Failures held the second position in the 2021 OWASP Top 10, and that 90% of applications tested by OWASP had security misconfigurations that compromised sensitive data in its OWASP Top 10 vulnerabilities and mitigation guide. Executives shouldn't get distracted by the category label. The business issue is exposed data.
What good remediation looks like
A healthcare platform that sends patient data over HTTP invites interception. A payment application that stores passwords with MD5 invites cracking if the database leaks. Unencrypted backups in a shared administrative environment create insider risk with almost no technical sophistication required.
The fix isn't custom cryptography. It's disciplined use of proven components and operational controls.
Use established libraries: OpenSSL, bcrypt, scrypt, Argon2, and libsodium beat homemade crypto every time.
Encrypt in transit and at rest: Enforce HTTPS and protect sensitive stored data with strong encryption and managed keys.
Protect privileged access: Multi-factor authentication for admin functions cuts off easy abuse paths.
Treat key management as its own system: Centralize secrets, rotate keys, and isolate high-value material.
What doesn't work is assuming encryption alone solves access problems, or deploying it inconsistently across backups, logs, exports, and replicas. Valiant Cyber Solutions typically validates this category during application testing, mobile testing, and cloud security reviews where secrets, backups, and session handling often drift from policy.
3. A03 Injection
Injection remains one of the fastest ways to turn a small input flaw into full application compromise. A login form concatenates input into a SQL query, and ' OR '1'='1 bypasses authentication. A search feature appends user input into a query and exposes customer records. A contact form passes input to a shell command and hands the server to an attacker.
A lot of teams think modern frameworks solved this. They didn't. Frameworks reduce risk when developers use them correctly.
What attackers actually test
Attackers look for every place your app treats user input as trusted instruction. SQL is only one target. They also test OS commands, directory lookups, template engines, and backend integrations that passively accept unsanitized data.
The reliable defense is boring and that's good. Parameterized queries, prepared statements, strict allowlists, context-specific escaping, and strong type validation stop most of the damage before it starts.
Parameterize queries: Never concatenate raw input into SQL, LDAP, shell, or template commands.
Validate by allowlist: Check type, format, range, and length before processing input.
Escape for the right context: HTML escaping won't protect a shell call, and SQL escaping won't protect a URL.
Review dangerous sinks: Focus code reviews on places where the app builds commands dynamically.
A short walkthrough helps teams see how quickly this class of flaw becomes material.
Attackers don't care whether the flaw came from legacy code, a rushed feature, or an AI-generated snippet. If input reaches an interpreter unsafely, they'll use it.
Valiant Cyber Solutions generally finds injection issues in web app, API, and mobile backend testing where business pressure created shortcuts around safe query patterns.
4. A04 Insecure Design
Insecure design is where security debt starts before a line of code ships. The password reset workflow allows unlimited attempts. Checkout trusts client-side price values. A financial transfer flow lacks MFA, session expiry, or meaningful abuse controls. None of those problems disappear with a patch sprint.
This is why executives should treat architecture as a primary control surface, not an abstract design exercise. The practical cost of a design flaw is that engineers can spend weeks fixing symptoms while the core abuse path remains open.
Where design reviews fail
Security teams often prioritize visible technical defects over logic flaws because logic flaws are harder to test, explain, and ticket. That's a mistake. The 2025 OWASP update promoted Insecure Design to rank #4, and the verified data provided for this topic notes that 60% of critical breaches stem from architectural flaws rather than code-level bugs. The same dataset states that 45% of new high-severity CVEs in 2024 originated from design logic gaps, not component vulnerabilities.
The most effective move is to force threat modeling into backlog grooming and sprint planning. Not as a giant workshop. As a lightweight habit tied to user stories and abuse cases.
Define abuse cases early: Ask how a user could bypass pricing, quotas, approvals, or tenant limits.
Write security requirements explicitly: Include authentication, logging, timeout, lockout, and data classification requirements in stories.
Review high-risk workflows: Password reset, funds transfer, admin delegation, and invitation flows need design review before implementation.
Test logic, not just code: Penetration tests should attempt price manipulation, workflow bypass, and transaction abuse.
Valiant Cyber Solutions addresses this category through threat-informed penetration testing and vCISO advisory that ties design review directly to delivery practices.
5. A05 Security Misconfiguration
Misconfiguration is what happens when secure design loses to default settings, deployment speed, and platform sprawl. A storage bucket goes public-read. A production error handler returns stack traces and SQL details. Jenkins reaches the internet with default credentials still active. None of that requires a complex exploit chain.
This category also creates a nasty operational trap. Teams rush to harden systems, then break visibility or introduce new issues during the cleanup.
What works in practice
The verified data for this topic states that 80% of organizations report A05 as their top recurring issue. It also notes that 34% of post-remediation breaches in a 2024 MITRE ATT&CK analysis happened because teams disabled logging or monitoring to cut noise while fixing misconfigurations. That trade-off is common in cloud environments where alerting is noisy and ownership is fragmented.
Operational warning: Hardening without drift detection becomes a recurring cleanup project, not a control.
Executives should push for baseline-driven configuration management, not heroics. In practice, the strongest programs set secure templates, scan infrastructure in CI/CD, preserve audit visibility, and review identity permissions alongside system settings. The same verified data notes that 52% of cloud-native misconfigurations now involve identity over-privilege in AWS Lambda and Azure Functions, and that engineering teams saw a 28% increase in privilege escalation incidents in Q1 2025 despite remediation efforts.
Start from hardened baselines: Use CIS-aligned standards where practical.
Automate drift detection: Catch insecure changes before production and continuously after deployment.
Fix identity, not just servers: Function roles, service accounts, and cloud IAM deserve the same attention as ports and headers.
Preserve observability during remediation: Don't suppress logs just to quiet the dashboard.
For cloud leaders, Valiant Cyber Solutions' AWS cloud security action plan for CISOs is a useful extension of this work. Valiant Cyber Solutions typically exposes these flaws through cloud configuration reviews, IAM assessments, and external attack-surface testing.
6. A06 Vulnerable and Outdated Components
A single outdated dependency can neutralize a well-funded security program. An app ships with an old Apache Struts component and exposes remote code execution. A Node.js service pulls a vulnerable lodash release. A Java service includes a risky log4j version. In each case, the application team didn't write the bug, but they still own the breach.
This category is often a governance problem disguised as a patching problem. Teams don't know what they run, who owns it, or whether the component is even necessary.
How to reduce dependency risk
What works is inventory, ownership, and controlled change. Build and maintain an SBOM. Track direct and transitive dependencies. Pin versions intentionally. Remove libraries that don't justify their risk.
What doesn't work is relying on ad hoc upgrades, or assuming package managers and container registries provide enough assurance by default. Modern applications inherit risk from plugins, base images, transitive packages, and abandoned libraries that nobody reviews after launch.
Keep an SBOM current: If you can't enumerate dependencies, you can't manage exposure.
Scan in the pipeline: Use dependency and container scanning before deployment, not after incident response starts.
Patch with ownership: Assign teams to critical frameworks and core services.
Reduce unnecessary packages: Every extra dependency expands the attack surface.
Organizations that need independent validation often pair dependency scanning with penetration testing and vulnerability assessment services from Valiant Cyber Solutions. That combination shows which known issues are exploitable in your environment.
7. A07 Identification and Authentication Failures
Authentication failures usually look harmless until attackers automate them. Weak passwords, predictable reset tokens, session fixation, reused credentials, and flawed recovery flows all lead to the same result. Someone gets into an account they shouldn't control.
A banking app that stores passwords with MD5 creates one kind of exposure. A password reset link that includes guessable user identifiers creates another. A portal with no meaningful rate limiting invites credential stuffing at scale.
Controls that hold up under attack
The strongest authentication programs don't depend on any single control. They layer password hygiene, MFA, session management, throttling, lockouts, and user notifications so one miss doesn't become an account takeover.
That matters because executives often fund SSO or MFA and assume the problem is solved. It isn't. If reset flows, token invalidation, and session handling are weak, attackers route around the visible controls.
Require strong credentials: Favor long passphrases and block weak defaults.
Put MFA on privileged and remote access first: Then expand coverage systematically.
Throttle and delay login attempts: Add rate limiting and exponential backoff on auth endpoints.
Hash passwords correctly: Use bcrypt, scrypt, or Argon2 with unique salts.
Validate recovery flows: Reset and recovery are part of authentication, not side features.
For organizations tightening workforce and third-party access, Valiant Cyber Solutions' guide to remote access security and defense fits directly into this category. Valiant Cyber Solutions typically validates these controls through application tests, external infrastructure testing, and phishing-resistant access reviews.
8. A08 Software and Data Integrity Failures
This category became more important because modern applications trust too much of their supply chain. Build agents pull packages, pipelines sign artifacts, registries host containers, plugins update automatically, and teams assume the path is safe if the brand looks familiar. Attackers know better.
The 2025 OWASP Top 10 introduced Software and Data Integrity Failures as a new category, expanding beyond outdated components to cover dependencies, build systems, and distribution infrastructure, according to SentinelOne's overview of the 2025 OWASP Top 10 update. That change matters because trusted systems now fail in trusted places.
Where supply chain controls break
A malicious npm package can exfiltrate credentials during build time. A compromised update process can distribute backdoored code. A pull request can pass functional review while inserting a credential-stealing task into a nightly job. Those aren't hypothetical patterns. They're exactly how mature adversaries avoid front-door defenses.
The same verified data for this topic also states that 72% of supply chain attacks in the 2023 to 2024 period succeeded because teams accepted unvalidated design assumptions in CI/CD pipelines. That points to a practical fix list.
Verify cryptographic signatures: Validate dependencies, updates, and release artifacts before promotion.
Harden CI/CD boundaries: Separate build, test, and deploy responsibilities.
Use controlled artifact repositories: Limit what can enter production.
Require review on critical paths: Guard workflow definitions, deployment scripts, and privileged pipeline changes.
Watch for anomalous dependency behavior: Unusual outbound traffic or build activity deserves scrutiny.
Valiant Cyber Solutions addresses this category through cloud and CI/CD security reviews, targeted red team exercises, and advisory support that tests whether your software factory can resist tampering.
9. A09 Logging and Monitoring Failures
A breach you can't reconstruct becomes a governance problem, not just a technical one. Failed logins occur, but no one alerts on the pattern. An administrator alters records, but the application doesn't preserve a reliable audit trail. Initial access happens weeks earlier, and the team discovers it only after customers report suspicious activity.
Logging failures don't create the initial weakness. They let attackers keep it.
What to log and why
The practical goal isn't to log everything. It's to log the events that matter for detection, response, and accountability. That means authentication activity, authorization decisions, data access, admin actions, configuration changes, and security-relevant errors with enough context to investigate.
Good logging answers four questions fast: who acted, what they touched, where they came from, and whether the action succeeded.
What works is centralized collection, correlation, alerting, and protection against tampering. What doesn't work is scattered app logs on ephemeral hosts, short retention, and no connection between application events and cloud or identity telemetry.
Capture security-relevant events: Especially auth, privilege changes, sensitive data access, and config modifications.
Include useful context: Timestamp, user or service identity, source IP, target resource, and outcome.
Centralize and correlate: Feed logs into a SIEM or equivalent platform.
Protect integrity: Restrict write access and prefer append-only storage where possible.
Retain enough history: Investigations often start after the first indicators appear.
Valiant Cyber Solutions often validates this category during red team and purple team work, focusing not just on whether an attack path exists, but on whether your team sees it in time.
10. A10 Server-Side Request Forgery
SSRF looks technical, but the business impact is simple. Your application becomes the attacker's proxy. A feature that fetches an image from a supplied URL gets abused to query internal services. A URL preview function reaches cloud metadata endpoints. A backend integration follows redirects into administrative interfaces that were never meant to face the internet.
The attacker doesn't need direct network access if your server will make the request for them.
How to contain the blast radius
This issue is common in modern architectures because applications fetch webhooks, previews, avatar images, PDFs, and third-party data all day. The danger isn't only data exposure. SSRF can also support internal reconnaissance and lateral movement if outbound access is broad.
The cleanest defense is to avoid arbitrary user-supplied fetches entirely. If the business needs the feature, constrain it hard.
Allowlist destinations: Only approved domains and protocols should be reachable.
Normalize and validate input: Reject IP literals, dangerous redirects, and unsupported schemes when they're not required.
Filter egress: Limit what application servers can reach on the network.
Isolate fetch services: Put them in constrained network zones with minimal privileges.
Bound requests: Set timeouts, size limits, and avoid returning raw response bodies to users.
Valiant Cyber Solutions typically finds SSRF through web application and cloud testing, especially where applications have access to internal APIs, metadata services, and broad outbound connectivity.
OWASP Top 10 Vulnerabilities Comparison
From Insight to Immunity Validate Your Defenses
Knowing the OWASP Top 10 is useful. Proving you can resist those attack paths is what matters. That's the gap many executive teams still underestimate. Policy says access is controlled, encryption is enforced, dependencies are managed, and logging is in place. Offensive testing shows whether those controls hold when an attacker chains small weaknesses together.
The OWASP Top 10 vulnerabilities should shape budget, engineering priorities, and oversight. They shouldn't sit in a slide deck as awareness material. Broken access control tells you to examine authorization models and tenant boundaries. Insecure design tells you to challenge business logic before release. Security misconfiguration tells you to standardize cloud and application baselines. Software and data integrity failures tell you to treat CI/CD and artifact trust as production security issues, not dev tooling details.
That shift matters because executives rarely lose sleep over a category name. They lose sleep over the consequences. Customer data exposure. Payment fraud. Administrative takeover. Service outage. Failed audit response. Weak incident reconstruction. The OWASP Top 10 becomes far more useful when every category maps to a business outcome and a validation method.
That's where Valiant Cyber Solutions fits. The firm's value isn't just finding bugs. It's validating real attack paths with adversary-simulated testing across applications, APIs, networks, cloud environments, and human workflows. A web application penetration test can expose broken access control or injection that scanners miss. A cloud review can uncover misconfiguration, identity overreach, and risky artifact paths. A red team exercise can test whether logging, monitoring, and response controls effectively detect the behavior leadership assumes is visible. A vCISO engagement can turn those findings into governance, prioritization, and board-level reporting that engineering teams can execute.
What works best is a loop. Test. Remediate. Retest. Then fix the process that allowed the flaw into production in the first place. That's how organizations stop treating the OWASP Top 10 as a recurring list of defects and start using it as a system for risk reduction.
