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High, CVSS 8.7amended

Nest: Middleware Bypass on Fastify via Trailing Slash

CVE-2026-54281GHSA-6v32-fjc9-9qf6

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (@nestjs/platform-fastify 11.1.24), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS 4.0
8.7 · CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N · score source
EPSS
  • CVE-2026-54281: 0.50% estimated exploitation activity in the next 30 days; percentile 42.77 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Impact An authentication bypass vulnerability exists in @nestjs/platform-fastify (confirmed on version 11.1.24, the latest available release at time of report). When middleware is registered through NestJS's MiddlewareConsumer.forRoutes() API on the Fastify adapter, an unauthenticated client can bypass the Nest middleware registered for that route by simply appending a trailing slash (/) to the request URL. This bypass works on the default Fastify adapter configuration — no special router options need to be enabled. Applications using the standard CRUD route shape (GET /resource and GET /resource/:id) are affected when they protect those routes with MiddlewareConsumer.forRoutes() middleware. Patches Fixed in @nestjs/platform-fastify@11.1.24 References Kudos goes to @a-tt-om

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 3 · amended ·

    Amended from ghsa record GHSA-6v32-fjc9-9qf6

  2. Revision 2 · amended ·

    Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

  3. Revision 1 · created ·

    Published from osv record GHSA-6v32-fjc9-9qf6

Agent brief

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# Patch Next advisory brief: CVE-2026-54281

Advisory: Nest: Middleware Bypass on Fastify via Trailing Slash
IDs: CVE-2026-54281, GHSA-6v32-fjc9-9qf6
Record: https://patchnext.com/advisories/cve-2026-54281 (revision 3, source checked 26 Oct 2026, 12:57 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: @nestjs/platform-fastify 11.1.24. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm @nestjs/platform-fastify: affected <= 11.1.23; fixed in 11.1.24

## Suggested inspection (read-only)
- `npm ls @nestjs/platform-fastify --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on @nestjs/platform-fastify.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-6v32-fjc9-9qf6 (OSV record GHSA-6v32-fjc9-9qf6 lists affected ranges: npm @nestjs/platform-fastify >=0 <11.1.24 (fixed))
- Verified: https://github.com/advisories/GHSA-6v32-fjc9-9qf6 (GitHub-reviewed advisory GHSA-6v32-fjc9-9qf6 lists affected ranges: npm @nestjs/platform-fastify >=0 <=11.1.23)

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