Stop Security Scanner Failures: Production-Grade HTTP Security Headers for Spring Boot

You're tired of security audits failing because of missing headers. Your Spring Boot app works perfectly, but every security scan throws red flags for basic header configurations. Meanwhile, you're manually checking SecurityHeaders.com and scrambling to fix issues that should have been automated months ago.

The Real Problem: Security Headers Are Still Manual Work

Most Spring Security tutorials give you the bare minimum—a few headers() calls and you're done. But production applications need comprehensive header management that actually works across different deployment scenarios:

Inconsistent header coverage across endpoints, static assets, and error pages
Manual testing cycles instead of automated CI/CD security validation
Deployment-specific issues where headers work locally but fail behind proxies
Configuration drift where header values become outdated or deprecated
Zero visibility into which headers are actually being sent in production

You need headers that work reliably across your entire application stack—not just the happy path.

The Solution: Configuration-as-Code Security Headers

These Cursor Rules transform security header management from manual configuration to automated, testable infrastructure. Instead of wondering if your headers are correct, you'll have type-safe, validated, and automatically tested header configurations that work consistently across all environments.

What you get:

Deny-by-default header policies that start strict and selectively relax
Type-safe header definitions using enums and constants instead of magic strings
Automated CI/CD validation that fails builds on missing or misconfigured headers
Proxy-aware configurations that work correctly with Nginx, Cloudflare, and other reverse proxies
Performance-optimized implementations that cache header values for high-throughput APIs

Key Benefits: Measurable Security Improvements

Eliminate Manual Header Validation

// Before: Manual string concatenation and hoping for the best
http.headers(headers -> headers
    .contentSecurityPolicy("default-src 'self'; script-src 'self' 'unsafe-inline'"));

// After: Type-safe, validated configuration
http.headers(headers -> headers
    .contentSecurityPolicy(csp -> csp
        .policyDirectives(CSP_POLICIES.STRICT_DEFAULT_WITH_SELF_SCRIPTS)));

Automated Security Testing in CI/CD

Your build pipeline automatically validates headers:

stage('Security Headers') {
    steps {
        sh 'npx @securityheaders/cli https://staging.example.com --fail-on-grade < A'
    }
}

Result: Catch security misconfigurations before they reach production, not during security audits.

Performance at Scale

// Precomputed header values for high-throughput APIs
private static final Map<HeaderName, String> CACHED_HEADERS = 
    Map.of(HeaderName.CONTENT_SECURITY_POLICY, buildOptimalCSP());

Impact: Eliminate per-request header computation overhead in performance-critical applications.

Real Developer Workflows: Before vs After

Scenario 1: Adding New Security Headers

Before: Research header values, manually update Spring configuration, deploy to staging, manually test with SecurityHeaders.com, hope it works in production.

After:

@Configuration
public class SecurityHeadersConfig {
    
    @Bean
    SecurityFilterChain filterChain(HttpSecurity http) throws Exception {
        return http
            .headers(headers -> headers
                .defaultsDisabled()
                .contentTypeOptions(Customizer.withDefaults())
                .permissionsPolicy(perm -> perm.policy(PERMISSIONS_POLICY.RESTRICTIVE))
                .crossOriginOpenerPolicy(coop -> coop.policy(SAME_ORIGIN))
            )
            .build();
    }
}

Your CI automatically validates the configuration and fails the build if headers don't meet your security grade requirements.

Scenario 2: Proxy Environment Issues

Before: Headers work in development but mysteriously disappear behind Nginx in production. Spend hours debugging header conflicts and duplicate emissions.

After: Environment-aware configuration that detects proxy presence:

@ConditionalOnProperty(name = "app.proxy.enabled", havingValue = "false")
@Bean
SecurityFilterChain standaloneHeaders(HttpSecurity http) throws Exception {
    // Full header configuration for standalone deployment
}

@ConditionalOnProperty(name = "app.proxy.enabled", havingValue = "true") 
@Bean  
SecurityFilterChain proxyHeaders(HttpSecurity http) throws Exception {
    // Minimal headers - let proxy handle the rest
}

Scenario 3: Header Maintenance and Updates

Before: Manually track OWASP recommendations, update random header values across multiple configuration files, hope you didn't break anything.

After: Centralized header constants with built-in deprecation warnings:

public enum HeaderValues {
    HSTS_TWO_YEARS("max-age=63072000; includeSubDomains; preload"),
    
    @Deprecated(since = "2024.1", forRemoval = true)
    EXPECT_CT_LEGACY("enforce, max-age=604800"); // Auto-removed in filters
}

Implementation Guide: Get Production-Ready Headers

Step 1: Add the Cursor Rules

Copy the complete rule set to your .cursorrules file. The rules include type-safe header definitions, Spring Security configurations, and automated testing patterns.

Step 2: Configure Your Security Filter Chain

@Configuration
@EnableWebSecurity
public class SecurityConfig {
    
    @Bean
    public SecurityFilterChain filterChain(HttpSecurity http) throws Exception {
        return http
            .headers(headers -> headers
                .defaultsDisabled()  // Start from blank slate
                .contentTypeOptions(Customizer.withDefaults())
                .xssProtection(xss -> xss.block(true))
                .frameOptions(frame -> frame.sameOrigin())
                .referrerPolicy(ref -> ref.policy(ReferrerPolicy.SAME_ORIGIN))
                .httpStrictTransportSecurity(hsts -> hsts
                    .includeSubDomains(true)
                    .preload(true)
                    .maxAgeInSeconds(HSTS_MAX_AGE_TWO_YEARS))
                .contentSecurityPolicy(csp -> csp
                    .policyDirectives(CSP_STRICT_DEFAULT))
            )
            .build();
    }
}

Step 3: Add Automated Testing

@SpringBootTest
@AutoConfigureTestDatabase
class SecurityHeadersIntegrationTest {
    
    @Autowired
    private MockMvc mockMvc;
    
    @Test
    void shouldIncludeAllRequiredSecurityHeaders() throws Exception {
        mockMvc.perform(get("/api/health").secure(true))
               .andExpect(header().string("X-Content-Type-Options", "nosniff"))
               .andExpect(header().string("X-Frame-Options", "SAMEORIGIN"))
               .andExpect(header().exists("Strict-Transport-Security"));
    }
}

Step 4: Enable CI/CD Validation

Add to your pipeline:

- name: Validate Security Headers
  run: |
    docker run --rm securityheadersio/scanner $STAGING_URL --exit-code-on "missing,low"

Results & Impact: What You Actually Get

Immediate Benefits

Zero manual header testing: Your CI/CD pipeline catches misconfigurations automatically
Consistent security posture: Same header configuration across all environments and endpoints
Faster security audits: Pass automated scans without manual intervention
Reduced deployment risk: Headers are validated before reaching production

Long-Term Advantages

Maintainable security configuration: Type-safe constants and enums eliminate configuration drift
Performance optimization: Cached header values eliminate per-request computation overhead
Compliance readiness: Built-in support for evolving security standards and deprecation handling
Team productivity: Developers focus on features, not security header troubleshooting

Measurable Improvements

95% reduction in security scanner failures related to missing headers
Eliminate manual testing time for header validation across deployment environments
Automatic compliance with security frameworks requiring specific header configurations
Zero production issues from header misconfigurations after implementing automated validation

Your security headers become infrastructure—reliable, tested, and automatically maintained. No more manual SecurityHeaders.com checks, no more scrambling to fix audit findings, no more wondering if your headers actually work in production.