Common Web Bugs
Concise explanations with safe, copy-ready snippets for prevention-focused learning.
SQL Injection
Happens when input is concatenated into SQL queries directly.
SELECT * FROM users WHERE email = ?
Path Traversal
Occurs when file paths are built from untrusted input without restrictions.
allowlist = ["report.pdf","guide.pdf"]
CSRF
Cross-site requests can trigger state changes if anti-CSRF controls are missing.
Set-Cookie: session=...; HttpOnly; Secure; SameSite=Lax
SSRF
Backend request features can be abused when user-provided URLs are not validated.
Allow outbound only to approved host allowlist
Auth Misconfiguration
Common issues include weak session timeout, missing MFA, and role confusion.
Session TTL: 15m idle / 8h absolute + MFA for sensitive actions
Rate Limiting Gaps
Login and reset endpoints need strict throttling and anomaly detection.
Limit: 5 attempts / 10 min / account + IP backoff
Real-World Bug Explanations (Sanitized)
- Case A: file export endpoint accepted path fragments and leaked internal files
- Case B: webhook fetcher allowed internal metadata requests due to missing URL allowlist
- Case C: account recovery endpoint lacked throttling and user enumeration protections