CVE-2026-33011
CVE-2026-33011 is a CWE-670 vulnerability in @nestjs/platform-fastify. O3 Security confirms whether CVE-2026-33011 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Nest Fastify HEAD Request Middleware Bypass
Blast Radius
Weekly download volume for affected packages — a proxy for how broadly this vulnerability is deployed.
@nestjs/platform-fastifynpmDescription
Nest is a framework for building scalable Node.js server-side applications. In versions 11.1.15 and below, a NestJS application using @nestjs/platform-fastify GET middleware can be bypassed because Fastify automatically redirects HEAD requests to the corresponding GET handlers (if they exist). As a result: middleware will be completely skipped, the HTTP response won't include a body (since the response is truncated when redirecting a HEAD request to a GET handler), and the actual handler will still be executed. This issue is fixed in version 11.1.16.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | @nestjs/platform-fastify | all versions | 11.1.16 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @nestjs/platform-fastify. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update @nestjs/platform-fastify to 11.1.16 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-33011 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-33011 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-33011. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-33011 in your dependencies?
O3 detects CVE-2026-33011 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.