Link to the code that reproduces this issue

https://codesandbox.io/p/devbox/angry-lalande-98zyn5

To Reproduce

1. require() a cjs module, for example in getServerSideProps or in a server component. Import location does not matter.
2. Inside of the module, try to access __dirname - it is /ROOT/... instead of the real path. import.meta.url works correctly though - this is not a valid workaround though, since this normally does not work in CommonJS.

Current vs. Expected behavior

__dirname should work the same as when using Webpack / be consistent with data reported from import.meta

Provide environment information

Node: 20.12.1
  npm: 10.5.0
  Yarn: 1.22.19
  pnpm: 8.15.6
Relevant Packages:
  next: 16.0.2-canary.34 // Latest available version is detected (16.0.2-canary.34).
  eslint-config-next: N/A
  react: 19.2.0
  react-dom: 19.2.0
  typescript: 5.9.3
Next.js Config:
  output: N/A

Which area(s) are affected? (Select all that apply)

Turbopack

Which stage(s) are affected? (Select all that apply)

next dev (local), next build (local), next start (local)

Additional context

No response