·SecureStartKit Team
Filter PII From Sentry in Next.js: 4 Hidden Leaks [2026]
Deleting cookies in beforeSend won't stop PII. Sentry's Next.js SDK still sends user emails, request bodies, and stack locals. Here's how to scrub it all.
42 articles
Deleting cookies in beforeSend won't stop PII. Sentry's Next.js SDK still sends user emails, request bodies, and stack locals. Here's how to scrub it all.
Stripe Checkout handles SCA and 3D Secure automatically in Next.js. Here are the 4 cases that hand the requires_action state machine back to you.
Stripe Checkout puts a Next.js SaaS in the lightest PCI scope (SAQ A), but four common mistakes widen it. See what keeps card data off your server.
Stripe retries webhooks for 3 days, then stops. Learn how to ack fast, dedup correctly, and reconcile missed events in Next.js with the Events API.
Committing a .env to share secrets leaks them into git history forever. Compare the safe ways to share environment variables across a Next.js team.
Most Firebase to Supabase guides port the data and stop. The 3 security-critical steps: Security Rules to RLS, the cutover window, the old project.
Backend-only queries don't help if you serialize the whole row. See what passing data from Server to Client Components leaks, and how to stop it.
Magic-byte checks pass polyglots and miss decompression bombs. Re-encode every image upload through Sharp to strip EXIF and neutralize payloads.
Rotating a leaked API key the wrong way logs out every user or breaks your webhooks. The zero-downtime runbook for Supabase, Stripe, and Resend keys.
A caught redirect() or a swallowed auth check makes Next.js fail open. Where error handling grants access by accident, and the fail-closed fix.
Rendering user HTML or Markdown in Next.js? A strict CSP isn't enough. The 5 render boundaries where XSS slips through, and the server-side fix.
Maintained Vercel WAF rules for the 10 documented AI scraper user agents: GPTBot, ClaudeBot, PerplexityBot, Bytespider, and 6 more. With route patterns.
5 Zod validation failure modes in Next.js Route Handlers: FormData coercion, coerce.boolean traps, body conflicts, missing CSRF, identity from URL.
Five production rate-limit failure modes for Next.js Server Actions: XFF off Vercel, fixed-window burst, distributed IPs, missing await, billing.
How to patch a critical Next.js dependency CVE in 30 minutes. The CVE-2025-55182 RSC RCE response playbook, npm audit limits, and the 5 traps.
Supabase MFA recovery without recovery codes: backup TOTP factor, audited service_role reset, AAL-preserving rebinding, and 5 lost-device failure modes.
Supabase Storage multi-tenant isolation: path-encoded RLS with tenant_id JWT claim, bucket-vs-path decision, and 5 cross-tenant leak modes.
Next.js 16 proxy.ts route protection breaks in 5 ways: matcher burns, setAll skipped, next= bypass, getSession trust, dropped cookies. The fix for each.
Supabase password reset breaks in 5 ways. Referer leaks, session fixation, token reuse, weak OTP windows, email enumeration. The fix for each.
Next.js ships zero security headers by default. The 7-header next.config.ts setup that gets you to A+, plus the COOP/Stripe popup trap.
Bot protection on Vercel in 2026: why a 403'd bot still costs you, what BotID and the WAF actually stop, when Cloudflare in front is worth it.
The 6 mechanical differences between Stripe one-time and subscription billing, the code surface each adds, and why SecureStartKit ships dual-mode.
Six Next.js environment variable leak modes (NEXT_PUBLIC drift, middleware fallthrough, build-time inlining, Vercel scope) and the architectural fixes.
Secure OAuth, magic links, and MFA in Supabase + Next.js. PKCE flow, redirect URL allowlists, AAL2 step-up, and 5 implementation failure modes.
Stripe webhook signature failing in Next.js? 5 causes: parsed body, JSON re-stringify, timestamp drift, wrong secret, missing idempotency.
Pre-launch security audit for Next.js + Supabase: 12 highest-impact checks of 30, in audit order, with triage rules. Run weeks before launch.
Supabase JWT lifecycle, ES256 asymmetric signing keys, httpOnly cookie storage, and getClaims vs getUser vs getSession for Next.js apps.
Multi-tenancy and RBAC in Supabase + Next.js. Tenant scoping via JWT claims + RLS, the composite index rule, and five cross-tenant leak modes.
OWASP Top 10:2025 mapped to Next.js + Supabase failure modes plus the architectural defenses that prevent each category. With 2026 CVEs.
CSRF, XSS, and SQL injection prevention in Next.js. Three architectural defenses tied to OWASP A05:2025 and the 2026 Next.js injection CVEs.
You shipped a Lovable, Cursor, or v0 prototype. Now you need a SaaS that won't get hacked. The 4-phase migration playbook for 2026.
Seven security checks every solo dev must verify before going live: auth, RLS, Zod, webhooks, headers, secrets, error handling. The pre-launch audit.
Five architectural patterns most Next.js SaaS templates skip: backend-only access, Zod everywhere, RLS deny-all, signed webhooks, server-only imports.
AI tools like Lovable, Cursor, Bolt, and Replit ship insecure code. The 2026 breach pattern, bug categories, and the architectural fix.
The architectural pattern that prevents Supabase data leaks. Server Actions, admin client, no NEXT_PUBLIC key for queries, ever.
Next.js 16's 'use cache' is easy to misuse. Cache the wrong thing and User A sees User B's data. The three directives explained safely.
A production security checklist for Next.js apps. Covers HTTP headers, CSP, environment variables, Server Actions, RLS, webhook verification, and more.
Claude Code CVEs, Google's $82K API key incident, 5,000+ repos leaking ChatGPT keys. Learn how AI tools expose your secrets and how to lock them down in Next.js.
Vibe coding tools like Cursor and v0 build apps fast, but they often ship vulnerabilities. Here is the technical audit checklist for Next.js and Supabase apps.
Server Actions are public HTTP endpoints. Validate every payload with Zod before any database call. Patterns for Next.js 16 and Zod 4 with CVE context.
The Lovable hack exposed 170+ apps through missing RLS. Here's what went wrong and the exact steps to secure your Supabase database.
5 architectural commitments fit in ~134 lines across a complete SaaS template. The speed-vs-security trade-off does not exist at the code layer.