A Simple Guide for Business and Non-Technical Readers
OWASP says the Top 10:2025 is the current release of its main awareness document for web application security. The 2025 list is: A01 Broken Access Control, A02 Security Misconfiguration, A03 Software Supply Chain Failures, A04 Cryptographic Failures, A05 Injection, A06 Insecure Design, A07 Authentication Failures, A08 Software or Data Integrity Failures, A09 Security Logging and Alerting Failures, and A10 Mishandling of Exceptional Conditions. OWASP also says this 2025 edition includes two new categories and one consolidation compared with the previous edition.
A simple way to explain the whole list is this:
A web app becomes unsafe when it trusts the wrong user, the wrong data, the wrong component, or the wrong behavior.
1. A01:2025 Broken Access Control
Explanation
Access control means users should only see and do what they are allowed to see and do. OWASP says broken access control happens when that rule fails, which can lead to unauthorized viewing, changing, deleting, or using data and business functions outside a user’s intended permissions. OWASP keeps this category at #1 in 2025 and notes that SSRF has been rolled into this category in the new edition.
Example
A normal employee changes a URL from /profile/123 to /profile/124 and suddenly sees another employee’s salary record. In another case, a standard user changes a hidden field or token and gains admin-level access. Those are classic access control failures.
How to reduce it
Use server-side permission checks for every request, deny access by default, do not trust client-side values, test for IDOR and privilege escalation, and review CORS, tokens, and direct object references carefully. The main goal is simple: the server must decide what each user is allowed to do every time.
Reference
OWASP, A01:2025 Broken Access Control.
2. A02:2025 Security Misconfiguration
Explanation
Security misconfiguration means the system is set up in an unsafe way. OWASP says this includes missing hardening, weak cloud permissions, unnecessary features, default accounts, insecure framework settings, and missing security headers. OWASP also says this category moved up from #5 in 2021 to #2 in 2025, showing how common configuration risk has become.
Example
A company deploys a web app with debug mode enabled, default admin credentials still active, and detailed error messages visible to users. An attacker does not need a complex exploit; they just use what the system is already exposing.
How to reduce it
Use secure default settings, remove unused services and sample pages, disable default accounts, review cloud permissions, turn off verbose errors in production, and make configuration review part of every release. A clean and minimal environment is usually a safer environment.
Reference
OWASP, A02:2025 Security Misconfiguration.
3. A03:2025 Software Supply Chain Failures
Explanation
OWASP says software supply chain failures are problems in how software is built, updated, distributed, or maintained. This now covers more than just “old libraries.” In 2025, OWASP expanded the old component-focused category into a broader view that includes dependencies, build systems, and distribution infrastructure. OWASP also notes this category was a top concern in the community survey.
Example
Your web app depends on a third-party package. That package is compromised, or your build pipeline pulls a malicious update. The application itself may look fine, but the weakness enters through the software chain around it.
How to reduce it
Track all dependencies, including transitive ones, scan for vulnerabilities regularly, subscribe to security advisories, document build and release changes, and protect repositories, package sources, CI/CD, and artifact storage. In short, secure the whole path from code to production, not just the app code itself.
Reference
OWASP, A03:2025 Software Supply Chain Failures.
4. A04:2025 Cryptographic Failures
Explanation
Cryptographic failures happen when sensitive data is not properly protected by strong encryption and safe key handling. OWASP says this category often leads to sensitive data exposure or full system compromise. In the 2025 edition, it remains one of the most serious risks.
Example
A website does not enforce HTTPS everywhere, so someone on a public Wi-Fi network intercepts a session cookie and hijacks the user’s account. Another common case is storing passwords with weak or fast hashes that attackers can crack quickly after a breach.
How to reduce it
Use TLS correctly, protect all sensitive traffic, store passwords with modern password hashing, manage keys safely, and only keep sensitive data when there is a clear business need. The simple rule is: if data matters, protect it both in transit and at rest.
Reference
OWASP, A04:2025 Cryptographic Failures.
5. A05:2025 Injection
Explanation
OWASP says injection happens when untrusted user input is sent to an interpreter, such as a database, browser, or command line, and the interpreter runs part of that input as commands. This category still covers classic problems like SQL injection and also includes XSS in the broader injection family.
Example
A login form takes a username and places it directly into a database query. Instead of entering a normal value, an attacker sends crafted input that changes the meaning of the query and extracts other users’ data. The same idea can happen with shell commands, templates, and browser scripts.
How to reduce it
Validate input, use parameterized queries, avoid building commands with string concatenation, sanitize output for the correct context, and keep dangerous interpreters away from raw user input. The app should never let user text become executable instructions.
Reference
OWASP, A05:2025 Injection.
6. A06:2025 Insecure Design
Explanation
Insecure design means the problem starts before coding. OWASP says this category focuses on design and architectural flaws, and calls for more threat modeling, secure design patterns, and reference architectures. A design flaw cannot be fully fixed by “clean coding” if the needed control was never designed in the first place.
Example
A money transfer feature has no step-up verification, no fraud limit, and no protection against abuse. Even if the code is bug-free, the business design itself is unsafe because attackers can misuse the workflow exactly as it was built.
How to reduce it
Do threat modeling early, define abuse cases, design security controls before development starts, and review architecture for trust boundaries, privilege levels, and misuse paths. Secure design is about asking “how could this feature be abused?” before users and attackers answer that question for you.
Reference
OWASP, A06:2025 Insecure Design.
7. A07:2025 Authentication Failures
Explanation
Authentication failures happen when the system cannot reliably confirm who the user is, or cannot protect the session after login. OWASP says this category includes weak passwords, missing MFA, poor recovery flows, session problems, and badly managed tokens. OWASP also notes the 2025 name is slightly simplified from the old “Identification and Authentication Failures.”
Example
A web app allows weak passwords, has no MFA, and does not lock out brute-force attempts. An attacker tries stolen credentials from another breach and gets into customer accounts. In another case, the app leaves session IDs in the URL, which makes account hijacking easier.
How to reduce it
Use MFA where possible, block brute force and credential stuffing, ban default credentials, check passwords against known weak-password lists, protect session tokens, and invalidate sessions correctly at logout or timeout. A good login system protects both the identity and the session.
Reference
OWASP, A07:2025 Authentication Failures.
8. A08:2025 Software or Data Integrity Failures
Explanation
OWASP says this category is about failing to maintain trust boundaries and verify the integrity of software, code, and critical data artifacts. It is narrower than the broader supply chain category and focuses more on unsafe assumptions around updates, code, and trusted data.
Example
A web app automatically accepts an update file, plugin, or configuration package without checking its signature or integrity. If an attacker changes that file on the way in, the application may trust and run something malicious.
How to reduce it
Verify software and data integrity, use signing and checksum validation where appropriate, enforce trusted update paths, protect CI/CD artifacts, and do not assume that code or critical data is safe just because it came from an internal or familiar source. Trust should be checked, not assumed.
Reference
OWASP, A08:2025 Software or Data Integrity Failures.
9. A09:2025 Security Logging and Alerting Failures
Explanation
OWASP says logging alone is not enough. This category covers failures to record important security events, failures to alert on them, and failures to respond in time. The 2025 wording now emphasizes alerting more clearly, because logs that no one notices do not help stop incidents.
Example
Attackers try thousands of login attempts, trigger server-side validation failures, and probe sensitive endpoints, but the application either records nothing useful or produces alerts that no one reviews. By the time the team notices, the breach is already large.
How to reduce it
Log all important auth, access control, and validation failures with enough context, keep logs long enough for investigation, make them easy for monitoring tools to consume, and define alert thresholds and escalation paths that someone actually follows. Good security logging should lead to action, not only storage.
Reference
OWASP, A09:2025 Security Logging and Alerting Failures.
10. A10:2025 Mishandling of Exceptional Conditions
Explanation
This is a new category in 2025. OWASP says it focuses on improper error handling, logical errors, failing open, and related problems caused by unusual or abnormal conditions. In simple terms, the application becomes unsafe when it does not know how to behave safely under stress, bad input, missing parameters, or environmental failure.
Example
A payment service loses connection to a backend check and, instead of denying the transaction safely, it “fails open” and approves the request. Another example is an app that crashes and reveals detailed internal errors, sensitive values, or an unpredictable state after malformed input.
How to reduce it
Handle exceptions close to where they happen, validate input early, define safe failure behavior, avoid revealing internal details in errors, and test abnormal conditions such as missing data, network failure, memory pressure, or permission issues. A secure system must also behave safely when things go wrong.
Reference
OWASP, A10:2025 Mishandling of Exceptional Conditions.
Final Takeaway
OWASP describes the Top 10 as a broad consensus on the most critical web application security risks, and the 2025 release updates that list using fresh data and community input. For business readers, the big lesson is simple: most serious web security problems happen when applications trust too much, check too little, or fail unsafely.
A practical summary is this:
Check access. Harden configuration. Control dependencies. Protect data. Validate input. Design safely. Secure login. Verify integrity. Log what matters. Fail safely.
Main References
OWASP, OWASP Top 10:2025.
OWASP, Introduction – OWASP Top 10:2025.
OWASP, A01–A10 category pages.
