OWASP Top 10: Essential Web App Security Risks for Frontend Developers

As a frontend developer, you might think backend is where most security battles are fought. But in today’s interconnected world, a vulnerable front door is all an attacker needs. Understanding OWASP’s Top 10 security risks isn’t just backend stuff it’s crucial knowledge for all developers, especially those building single-page apps (SPAs) or integrating with APIs.

In this blog, we’ll walk through all 10 security risks using one consistent example: a fictional SaaS platform called DevSync, a project management tool used by thousands of developers globally. We’ll explain each OWASP category with practical frontend-focused context and real-world breaches.

Broken Access Control

Risk: Users can access functionality or data they shouldn’t.

Example in DevSync: A frontend dev exposes the /admin route in the React Router thinking “only admins will see this anyway.” But the route isn’t protected on the backend  so any logged-in user who manually navigates to /admin can access user management features.

Real Attack Parallel: GitHub once had a vulnerability allowing users to add SSH keys to other accounts by manipulating API requests.

🔹Fix (Frontend Insight):

• Never rely on UI alone to enforce roles.
• Always validate permissions on the backend.
• Use route guards and role-based rendering in React, but don’t skip server checks.

Cryptographic Failures

Risk: Sensitive data is sent or stored without proper encryption.

Example in DevSync: The frontend fetches user profile info over HTTP instead of HTTPS on a coffee shop Wi-Fi, an attacker intercepts the traffic and grabs tokens and emails.

Real Attack Parallel: Equifax’s 2017 breach involved unencrypted sensitive data (among other flaws), exposing millions of SSNs.

🔹Fix:

• Enforce HTTPS always.
• Avoid storing sensitive data in localStorage or sessionStorage.
• If encrypting data client-side (e.g. end-to-end encrypted chat), use strong, vetted libraries.

Injection

Risk: Malicious input is interpreted as code.

Example in DevSync: A search bar in the frontend sends queries directly to an API that constructs a SQL query like:

SELECT * FROM projects WHERE name LIKE ‘%${search}%’

An attacker types ‘ OR ‘1’=’1 and now they get access to all projects.

Real Attack Parallel: The 2008 Heartland breach leaked 100M+ credit cards using SQL injection.

🔹Fix (Frontend Dev Role):

• Always validate and sanitize inputs, even in the UI.
• Don’t interpolate user data into queries the backend should use prepared statements.
• Escape user inputs shown in UI to avoid reflected injection attacks.

Insecure Design

Risk: Poorly thought-through security design that can’t be fixed by patches.

Example in DevSync: Devs allow unlimited password resets without cooldown or CAPTCHA. Attackers abuse this to spam users or brute-force reset links.

🔹Fix:

• Collaborate with backend & product on secure design patterns.
• Review workflows e.g., auth flows, payment handling for abuse vectors.
• Think like an attacker: what happens if someone abuses this button, page, or feature?

Security Misconfiguration

Risk: Insecure default settings, error leaks, unnecessary features.

Example in DevSync: The app runs in development mode with detailed error messages. When a frontend request fails, the API responds with a full stack trace revealing file paths and dependencies.

Real Attack Parallel: Verizon’s 2017 breach was worsened by misconfigured S3 buckets exposing data.

🔹Fix:

• Never show detailed errors to users.
• Remove debug tools in production builds (e.g. React DevTools hooks).
• Keep API base URLs, credentials, and config values out of the frontend build.

Vulnerable and Outdated Components

Risk: Using libraries with known exploits.

Example in DevSync: The frontend uses an outdated version of lodash with a prototype pollution vulnerability. An attacker sends a payload that corrupts object properties, leading to privilege escalation.

Real Attack Parallel: Event-Stream NPM package was backdoored to steal Bitcoin wallets.

🔹Fix:

• Run npm audit regularly.
• Avoid blindly installing libraries.
• Remove unused packages.
• Follow SemVer and security release notes.

Identification and Authentication Failures

Risk: Weak login, poor session handling, missing 2FA.

Example in DevSync: After login, a JWT token is stored in localStorage. On public Wi-Fi, an attacker uses a packet sniffer and grabs the token now they can impersonate the user.

Real Attack Parallel: Twitter (2020) attackers used social engineering and weak controls to hijack verified accounts.

🔹Fix:

• Use HttpOnly cookies for sensitive tokens (prevents XSS theft).
• Enforce strong passwords and MFA.
• Invalidate tokens on logout or role change.
• Use token rotation and refresh token expiry limits.

Software and Data Integrity Failures

Risk: Trusting components or data without verification.

Example in DevSync: Frontend loads a third-party script (analytics.js) over HTTP from an unknown CDN. One day, that file is replaced with malicious JS that logs keystrokes.

Real Attack Parallel: The SolarWinds hack inserted malicious updates into trusted software.

🔹Fix:

• Use subresource integrity (SRI) for CDN scripts.
• Host critical scripts yourself.
• Monitor the integrity of build chains (CI/CD pipelines, NPM scripts).

Security Logging and Monitoring Failures

Risk: You don’t know when you’re under attack.

Example in DevSync: A user gets 100 login failures in 2 minutes no alert, no logs, no rate limiting. The attacker eventually succeeds.

Real Attack Parallel: Capital One’s 2019 breach involved missing alert triggers that allowed massive data exfiltration to go unnoticed.

🔹Fix (Frontend & DevOps Insight):

• Track key events: login attempts, privilege changes, password resets.
• Don’t log sensitive data (like passwords or tokens).
• Use client-side logging (e.g., Sentry) for error monitoring with redaction.

Server-Side Request Forgery (SSRF)

Risk: Server fetches malicious URLs.

Example in DevSync: The frontend allows users to upload images by URL. It sends that URL to the backend for validation. But attackers submit http://localhost:8000/internal-config, letting the backend leak sensitive internal data.

Real Attack Parallel: The 2019 Capital One breach used SSRF to access AWS metadata services.

🔹Fix:

• Never blindly allow external URLs from users.
• Backend should whitelist trusted domains and block internal IPs.
• Avoid passing URLs from frontend to backend without scrutiny.