@jmondi/url-to-png is an open source URL to PNG utility featuring parallel rendering using Playwright for screenshots and with storage caching via Local, S3, or CouchDB. The package includes an `ALLOW_LIST` where the host can specify which services the user is permitted to capture screenshots of. By default, capturing screenshots of web services running on localhost, 127.0.0.1, or the [::] is allowed. If someone hosts this project on a server, users could then capture screenshots of other web services running locally. This issue has been addressed in version 2.1.1 with the addition of a blocklist. Users are advised to upgrade. There are no known workarounds for this vulnerability.

Affected: npm: @jmondi/url-to-png

### Summary

The maintainer been contemplating whether FTP or other protocols could serve as useful functionalities, but there may not be a practical reason for it since we are utilizing headless Chrome to capture screenshots. The argument is based on the assumption that this package can function as a service.

The package includes an `ALLOW_LIST` where the host can specify which services the user is permitted to capture screenshots of. By default, capturing screenshots of web services running on localhost, 127.0.0.1, or the [::] is allowed.

The maintainer is of the opinion that the package should also have a blacklist due to a potential vulnerability (or rather design oversight). If someone hosts this on a server, users could then capture screenshots of other web services running locally.

Unless this is strictly for web pages. Something similar here: https://github.com/follow-redirects/follow-redirects/issues/235 (localhost is intended for end users or hosts to deny, and the package is for HTTP/HTTPS.)

This is marked as a `LOW` since the maintainer is not sure if this is a vulnerability, but it's still best to highlight it. :)

### PoC

Have a service like so running locally:

```js const http = require("http")

const server = http.createServer((req, res) => { console.log("Received headers:", req.headers) res.writeHead(200, { "Content-Type": "text/plain" }) res.end("Something private! But Hello from Server 2 :)") })

server.listen(3001, () => { console.log("Serv…