# NestJS platform-fastify authentication bypass via URL normalization

Source: https://junglewise.ai/threats/nestjs-platform-fastify-authentication-bypass-via-url-normalization-7f9dc4ea  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-02-27. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

Severity: medium · CVSS 4 · Published 2026-02-27

NestJS is a popular Node.js framework for building server applications, and @nestjs/platform-fastify is an adapter that integrates the Fastify web server. When Fastify's path-normalization options are enabled, an attacker can bypass authentication and authorization middleware by manipulating URL paths, allowing unauthorized access to protected resources or functionality.

Technologies: [@nestjs/platform-fastify (npm)](https://junglewise.ai/threats/technologies/nestjs-platform-fastify). Vendors: [npm](https://junglewise.ai/threats/vendors/npm).

## Quick answers

**Is This vulnerability exploited in the wild?** No. Junglewise Threat Intelligence has no report of This vulnerability being exploited in the wild.

**How severe is This vulnerability?** Medium severity, with a CVSS score of 4, published 27 February 2026.

**Which products and versions are affected?** @nestjs/platform-fastify (npm) SEMVER:introduced=0,fixed=11.1.14.

**Is there a fix for This vulnerability?** Yes. @nestjs/platform-fastify (npm): upgrade to 11.1.14 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is This vulnerability attacked?** It is attacked over the network, in a software library.

**Am I affected?** Check whether you run @nestjs/platform-fastify (npm) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- @nestjs/platform-fastify (npm): upgrade to 11.1.14 or later

  ```sh
  npm install @nestjs/platform-fastify@11.1.14
  ```


## Technical details

The vulnerability is an authorization bypass (CWE-863) in @nestjs/platform-fastify that occurs when Fastify's path-normalization settings are active. By crafting specially normalized URLs, an attacker can circumvent authentication/authorization middleware checks without requiring credentials. The attack is network-accessible with no user interaction needed. The vulnerability affects @nestjs/platform-fastify versions before 11.1.14; a fix is available in version 11.1.14 and later.

## Affected products

- NestJS @nestjs/platform-fastify before 11.1.14

## Timeline

- 2026-02-27: disclosed
- 2026-02-27: patched: patch released as version 11.1.14
- 2026-03-02: other: advisory withdrawn as duplicate of GHSA-r4wm-x892-vjmx

## References

- [https://fluidattacks.com/advisories/neton](https://fluidattacks.com/advisories/neton)

## Related threats

- [NestJS authentication bypass in @nestjs/platform-fastify via trailing slash](https://junglewise.ai/threats/cve-2026-54281-nestjs-authentication-bypass-in-nestjs-platform-fastify-via)
- [NestJS platform-fastify HEAD request middleware bypass](https://junglewise.ai/threats/cve-2026-33011-nestjs-platform-fastify-head-request-middleware-bypass)
- [NestJS auth bypass in @nestjs/platform-fastify](https://junglewise.ai/threats/cve-2026-2293-nestjs-auth-bypass-in-nestjs-platform-fastify)
- [NestJS Fastify URL encoding middleware bypass](https://junglewise.ai/threats/cve-2025-69211-nestjs-fastify-url-encoding-middleware-bypass)