Web apps are everywhere in your APIs, your customer portal, your CRM, and your internal tools. And attackers love to target them. When Wyrdex conducts real-world web application penetration tests, we don’t just uncover textbook vulnerabilities we find critical security flaws actively present in production environments today.
These issues can enable hackers to steal data, gain system access, damage your brand, and cause compliance failures. Often, businesses had no idea their apps were vulnerable until we showed them using real-world attack scenarios.
This article outlines the 10 most common vulnerabilities we discover in real-world web application penetration tests, why they matter, and how to fix them.
1. Broken Access Controls
The most frequent and dangerous web app flaw is broken access control.
Examples:
- A regular user can access admin-only features
- An unauthenticated user can view private profiles
- One client can access another client’s reports or invoices
Cause:
Developers often rely on front-end controls (e.g., hiding buttons) rather than enforcing permissions on the backend.
Why it matters:
Attackers can escalate privileges, access sensitive data, or hijack user accounts.
How to fix it:
Enforce strict server-side access controls on every request. Implement role-based access control (RBAC), check for both horizontal and vertical privilege escalation, and validate session tokens.
2. SQL Injection (Yes, Still)
Despite being widely known, SQL injection continues to plague real-world applications.
Real impacts we’ve seen:
- Full database extraction
- Authentication bypass
- Theft of usernames, passwords, credit cards, or medical records
Cause:
Un sanitized user input is directly inserted into SQL queries.
Why it matters:
SQLi can lead to total database compromise and potentially backend takeover.
How to fix it:
Always use prepared statements (parameterized queries). Never trust user input sanitize, validate, and escape it consistently.
3. Cross-Site Scripting (XSS)
XSS allows attackers to inject JavaScript into pages viewed by other users. It’s used for phishing, session hijacking, and in-browser malware.
Real-world consequences:
- Stolen session cookies or tokens
- Redirecting users to malicious sites
- Keylogging credentials
Common XSS hotspots:
Comment boxes, user profile fields, search results, and dynamic URLs.
Why it matters:
Attackers can hijack the browser experience of your users.
How to fix it:
- Sanitize and encode output (not just input)
- Use libraries like DOMPurify
- Set strong Content Security Policy (CSP) headers
4. Insecure Direct Object References (IDOR)
IDOR flaws occur when object identifiers (like user IDs or filenames) are not properly validated.
Example:
- A user can access /invoice/123.pdf
- Changing it to /invoice/124.pdf retrieves another client’s invoice
Why it matters:
Attackers can view or manipulate data they shouldn’t have access to.
How to fix it:
- Never trust hidden fields or sequential URLs
- Enforce authorization checks on the backend
- Use random, non-guessable identifiers
5. Security Misconfigurations
In live environments, we often find default admin panels, outdated components, verbose error messages, or debug modes left active.
Common examples:
- Admin dashboards with no IP restrictions
- WordPress plugins with known CVEs
- HTTP headers leaking technology stack info
Why it matters:
Misconfigurations give attackers clues to exploit your environment.
How to fix it:
- Harden server configurations
- Disable detailed error messages in production
- Keep frameworks and plugins up to date
- Use secure headers like X-Content-Type-Options, Strict-Transport-Security
6. Insecure Authentication Flows
Weak authentication allows attackers to brute-force, hijack sessions, or reuse stolen credentials.
Real-world examples:
- Password spraying attacks across multiple accounts
- Session cookie replay
- Credential stuffing with breached passwords
Why it matters:
Authentication is your first line of defense if it fails, nothing else matters.
How to fix it:
- Enforce MFA for all users
- Implement rate limiting, account lockouts, and monitoring
- Regenerate session tokens on login
- Use secure cookie flags (HttpOnly, Secure, SameSite)
7. Vulnerable Libraries and Dependencies
Web apps rely on third-party components. Even if your code is secure, outdated libraries introduce serious risks.
What we see:
- jQuery versions with XSS vulnerabilities
- Unsafe versions of Spring, Struts, or Log4j
- NPM packages with malicious maintainers
Why it matters:
Attackers scan for apps using vulnerable libraries and exploit them directly.
How to fix it:
- Run regular dependency checks (e.g., npm audit, pip-audit, OWASP Dependency-Check)
- Subscribe to CVE feeds
- Use tools like GitHub Dependabot or Snyk
8. Insufficient Logging and Monitoring
Many apps don’t log security events properly or fail to monitor them altogether.
Questions we ask during tests:
- Was the suspicious activity detected?
- Did anyone get alerted?
- Are logs tamper-proof and backed up?
Often, the answer is no.
Why it matters:
Without logging and alerts, breaches go undetected. Attackers can erase traces unnoticed.
How to fix it:
- Log failed auth, privilege changes, and critical actions
- Use SIEM or a MSSP for real-time log analysis
- Ensure logs are immutable, encrypted, and backed up
9. Broken Business Logic
These flaws aren’t due to bad code but bad design.
Real cases:
- Skipping payment by manipulating workflow
- Abusing discounts or cart logic for repeated discounts
- Creating unlimited free-trial accounts
Why it matters:
Attackers exploit flawed logic for fraud, abuse, or privilege escalation and these bugs often go unnoticed.
How to fix it:
- Test workflows from an attacker’s perspective
- Use threat modeling during design
- Conduct logic-focused penetration tests regularly
10. Insecure APIs
Most modern web apps rely on REST or GraphQL APIs. These often bypass frontend validation or expose too much data.
What we’ve found:
- No authentication on critical endpoints
- Unrestricted access to user data
- Input fields leading to injection
- Overly verbose responses revealing internal structures
Why it matters:
APIs are now one of the top targets for attackers.
How to fix it:
- Authenticate all endpoints
- Validate inputs and sanitize outputs
- Enforce rate limiting
- Follow OWASP API Security Top 10
Why These Problems Keep Happening
Web application vulnerabilities persist because:
- Dev teams move fast and prioritize features
- Security testing is treated as a checkbox
- Pen tests are viewed as one-time tasks
But one missed flaw can cost everything:
- Customer data breaches
- Regulatory fines (GDPR, PCI, HIPAA)
- Entry points for ransomware
- Business loss and reputation damage
That’s why companies of all sizes choose Wyrdex.
How Wyrdex Helps You Find and Fix These Weaknesses
Wyrdex is an MSSP that prioritizes real-world cybersecurity. We provide comprehensive web application penetration testing not just checkbox scans.
We simulate real-world attacks to:
- Identify vulnerabilities in code, logic, and configuration
- Ethically exploit them to demonstrate impact
- Deliver actionable, prioritized remediation reports
- Re-test after fixes are applied
We also offer:
- Ongoing monitoring
- Vulnerability patching
- Threat intelligence
- Developer training
Whether you run a B2B SaaS, a fintech app, or a healthcare platform Wyrdex helps you keep your web apps secure.
Don’t Let Hackers Find the Flaw Before You Do
Hackers don’t care how new your app is.
They care how easy it is to get in.
Don’t wait for an incident to take security seriously. One missed vulnerability can jeopardize your business.