Avoid allowing access to unintended directories or files

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Metadata

ID: typescript-express/path-traversal

Language: TypeScript

Severity: Warning

Category: Security

CWE: 22

Description

By not sanitizing user input prior to using it in path resolution methods you open your application’s access to unintended directories and files.

If you’re using replace on a user input, this rule will assume you’ve done so correctly and will not report a violation

Learn More

OWASP path traversal

Non-Compliant Code Examples

import path from "path";

app.get("/", (req: Request, res: Response) => {
  path.join("/user/", req.params.path)

  const pathname = path.join("/public/", req.body.foo)
  path.resolve(pathname)

  path.resolve(__dirname, req.body.foo)
  path.resolve(__dirname, `${req.body.foo}`)
})

Compliant Code Examples

import path from "path";

app.get("/", (req: Request, res: Response) => {
  path.join("/user/", req.params.path.replace(/^(\.\.(\/|\\|$))+/, ''))

  const pathname = path.join("/public/", req.body.foo.replace(/^(\.\.(\/|\\|$))+/, ''))
  path.resolve(pathname)

  path.resolve(__dirname, req.body.foo.replace(/^(\.\.(\/|\\|$))+/, ''))
  path.resolve(__dirname, `${req.body.foo.replace(/^(\.\.(\/|\\|$))+/, '')}`)
})