Insecure Cookie Configuration
Last updated: January 12, 2026
Insecure cookies lack proper security flags, making them vulnerable to theft via XSS, interception over HTTP, or cross-site request forgery.
Scan for This VulnerabilityWhat is Insecure Cookie Configuration?
Cookies store sensitive session data. Without proper flags, they can be stolen through JavaScript (if HttpOnly is missing), intercepted over HTTP (if Secure is missing), or exploited in CSRF attacks (if SameSite is missing). These flags are your last line of defense for session security.
Why It's Dangerous
This vulnerability can allow attackers to access sensitive data, compromise user accounts, or gain unauthorized control over your application. In AI-generated code, this issue is particularly common because security measures are often deprioritized in favor of rapid feature development.
Why AI Code Is Vulnerable
AI code generation tools focus on producing functional code quickly. They often generate patterns that work correctly but lack the defensive measures experienced security engineers would implement. This makes insecure cookie configuration particularly prevalent in vibe-coded applications.
Understanding the Technical Details
Insecure Cookie Configuration is classified as a medium-severity vulnerability because of its potential to cause significant damage to your application and users. Understanding the technical mechanics helps you recognize and prevent this issue in your own code.
This vulnerability typically occurs when security controls are either missing entirely, improperly configured, or incorrectly implemented. In many cases, the code appears to work correctly during development and testing, but the security flaw becomes exploitable once the application is deployed and accessible to malicious actors.
Attackers actively scan for this type of vulnerability using automated tools. Once discovered, exploitation can be rapid—often within hours of your application going live. The consequences range from data theft and account takeover to complete system compromise depending on the application's architecture.
For vibe-coded applications built with platforms like Lovable, Bolt.new, Replit, or v0.dev, this vulnerability appears in roughly 20-40% of deployments according to security research. The AI-generated patterns often follow insecure defaults that require manual security hardening.
How It Happens
- Default cookie settings not hardened
- Framework doesn't set secure flags by default
- HttpOnly removed for JavaScript access
- Testing with Secure=false and not changing for production
Impact
Session hijacking through XSS attacks
Cookie interception on non-HTTPS connections
Cross-site request forgery (CSRF) attacks
Account takeover through stolen sessions
How to Detect
- Check cookies in browser DevTools > Application > Cookies
- Look for missing HttpOnly, Secure, SameSite flags
- Run VAS to analyze cookie security
How to Fix
Set HttpOnly flag
Prevents JavaScript from accessing the cookie, protecting against XSS.
// Cookie should have:
Set-Cookie: session=abc123; HttpOnlySet Secure flag
Cookie only sent over HTTPS connections.
Set-Cookie: session=abc123; SecureSet SameSite attribute
Protects against CSRF attacks.
Set-Cookie: session=abc123; SameSite=Lax
// or SameSite=Strict for maximum protectionComplete secure cookie example
All security flags combined.
Set-Cookie: session=abc123; HttpOnly; Secure; SameSite=Lax; Path=/Commonly Affected Platforms
Prevention Best Practices
The most effective approach to insecure cookie configuration is prevention. Implementing security measures during development is significantly easier and less costly than remediating vulnerabilities after deployment.
Security-First Development
When using AI code generation tools, always review the generated code for security implications. AI tools prioritize functionality over security, so treat all generated code as requiring security review. Establish a checklist of security requirements specific to your application type and verify each before deployment.
Continuous Security Testing
Integrate security scanning into your development workflow. Run scans after major code changes, before deployments, and on a regular schedule for production applications. Early detection of vulnerabilities reduces remediation costs and prevents potential breaches.
Defense in Depth
Never rely on a single security control. Implement multiple layers of protection so that if one control fails, others still protect your application. For example, combine authentication, authorization, input validation, and output encoding to create comprehensive protection against attacks.
Stay Informed
Security threats evolve constantly. Follow security researchers, subscribe to vulnerability databases, and monitor your dependencies for known issues. Understanding emerging threats helps you proactively protect your applications before attackers exploit new techniques.
Is Your App Vulnerable?
VAS automatically scans for insecure cookie configuration and provides detailed remediation guidance with code examples. Our scanner specifically targets vulnerabilities common in AI-generated applications.
Scans from $5, results in minutes. Get actionable results with step-by-step fix instructions tailored to your stack.
Get Starter ScanFrequently Asked Questions
What's the difference between HttpOnly and Secure flags?
HttpOnly prevents JavaScript from reading the cookie (protects against XSS stealing sessions). Secure ensures the cookie is only sent over HTTPS (protects against man-in-the-middle interception). Use BOTH: HttpOnly protects the cookie at rest, Secure protects it in transit.
When should I NOT use HttpOnly?
Only skip HttpOnly if your JavaScript legitimately needs to read the cookie value (like a CSRF token displayed in the UI). For session/auth cookies, ALWAYS use HttpOnly. If your app reads document.cookie to get session data, refactor to use a different mechanism.
What's the difference between SameSite=Lax and Strict?
Strict: cookie never sent on cross-site requests (breaks OAuth callbacks, links from emails). Lax: cookie sent on top-level navigation (GET) but not on POST or embeds. Use Lax for auth cookies in most apps. Use Strict only if you're sure users don't arrive via external links.
Why does my auth break with SameSite=Strict?
Strict blocks cookies on ANY cross-origin navigation. Common breaks: OAuth redirects, email 'verify account' links, links from other sites. Switch to SameSite=Lax which allows cookies on top-level navigations (clicking links) but blocks cross-site form submissions and embeds.