Top 30 Web App Exploits for Bug Bounty

If you’re serious about bug bounty hunting or web application security testing, you must understand the most common web vulnerabilities used in real-world attacks.
This guide covers 30 critical web app exploits every ethical hacker should know. These vulnerabilities appear frequently in bug bounty programs, penetration testing reports, and real-world breaches.
Let’s break them down in a simple and practical way 🚀

1️⃣ XSS (Cross-Site Scripting) 🧨​

Allows attackers to inject malicious JavaScript into web pages viewed by other users.
Example payload:

<script>alert('XSS')</script>

Impact:

• Session hijacking
• Account takeover
• Credential theft

2️⃣ SQL Injection (SQLi) 💉​

Occurs when user input is not properly sanitized in database queries.
Example: ' OR 1=1--
Impact:

• Data extraction
• Authentication bypass
• Database takeover

3️⃣ CSRF (Cross-Site Request Forgery) 🎭​

Forces users to perform unwanted actions while authenticated.
Impact:

• Password changes
• Fund transfers
• Account modifications

4️⃣ IDOR (Insecure Direct Object Reference) 🔓​

Occurs when users can access resources by changing IDs.
Example: /api/user?id=1001
Changing ID may expose other users’ data.

5️⃣ SSRF (Server-Side Request Forgery) 🌐​

Forces the server to make internal requests.
Impact:

• Access internal services
• Cloud metadata exposure
• Pivot attacks

6️⃣ RCE (Remote Code Execution) 💀​

Allows execution of commands on the server.
Example (concept):

<?php system($_GET['cmd']); ?>

Impact:

• Full server compromise

7️⃣ LFI / RFI 📁​

Local or Remote File Inclusion vulnerabilities.
Example: ?page=../../etc/passwd
Impact:

• File disclosure
• Possible RCE

8️⃣ SSTI (Server-Side Template Injection) 🧩​

Injection inside template engines.
Impact:

• Remote command execution
• Data exposure

9️⃣ Open Redirect 🔁​

Allows redirection to malicious domains.
Impact:

• Phishing attacks
• Token leakage

🔟 HTTP Request Smuggling 📦​

Manipulates HTTP parsing inconsistencies between servers.
Impact:

• Bypass security controls
• Cache poisoning

11️⃣ Web Cache Deception 🧠​

Forces sensitive content to be cached publicly.
Impact:

• Private data exposure

12️⃣ Broken Access Control 🚪​

Improper permission enforcement.
Impact:

• Privilege escalation
• Unauthorized access

13️⃣ JWT Forgery / None Algorithm Abuse 🔑​

Improper JWT validation.
Impact:

• Authentication bypass
• Account takeover

14️⃣ CORS Misconfigurations 🌍​

Improper Cross-Origin Resource Sharing policies.
Impact:

• Sensitive data theft

15️⃣ Mass Assignment ⚙️​

Allows modifying hidden object properties via request body.
Impact:

• Privilege escalation

16️⃣ Business Logic Flaws 🧮​

Application logic mistakes.
Impact:

• Free purchases
• Discount abuse
• Workflow bypass

17️⃣ Broken Authentication 🔐​

Weak session handling or login logic.
Impact:

• Account takeover

18️⃣ Path Traversal 📂​

Access files outside intended directory.
Example: ../../../etc/passwd

19️⃣ Prototype Pollution 🧬​

Modifies JavaScript object prototypes.
Impact:

• XSS
• Application logic manipulation

20️⃣ Host Header Injection 🏷️​

Manipulating Host header in requests.
Impact:

• Password reset poisoning
• Cache poisoning

21️⃣ Clickjacking 🖱️​

Tricking users into clicking hidden elements.
Defense:

• X-Frame-Options header

22️⃣ Subdomain Takeover 🌐​

Occurs when DNS points to deleted resources.
Impact:

• Domain hijacking

23️⃣ Deserialization Attacks 📦​

Unsafe object deserialization.
Impact:

• Remote Code Execution

24️⃣ Rate Limiting Bypass ⏱️​

Bypassing brute-force protection.
Impact:

• Account compromise

25️⃣ Misconfigured S3 Buckets / Exposed Secrets ☁️​

Public cloud storage exposure.
Impact:

• Data leaks

26️⃣ GraphQL Misconfigurations 📊​

Includes:

• Introspection abuse
• Injection
• Broken field-level authorization

Impact:

• Sensitive data extraction

27️⃣ HTTP Parameter Pollution (HPP) 🔀​

Duplicate parameters to confuse backend logic.
Impact:

• Authentication bypass
• Logic flaws

28️⃣ WebSocket Hijacking 🔌​

Insecure WebSocket implementations.
Impact:

• Session hijacking

29️⃣ OAuth / SSO Misconfigurations 🔗​

Improper third-party login validation.
Impact:

• Account takeover

30️⃣ Race Condition 🏎️​

Multiple requests executed simultaneously to abuse logic.
Impact:

• Double spending
• Coupon abuse
• Privilege escalation

Final Thoughts 🎯​

These 30 web application vulnerabilities appear regularly in:

• Bug bounty programs
• Penetration testing reports
• Real-world cyber attacks

If you want to become a successful bug bounty hunter or ethical hacker, mastering these exploits is essential.
Always test legally and responsibly in authorized environments only 🔐
Keep learning. Keep practicing. Stay ethical 🚀💻