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MEDIUM5.3

GHSA-vvmv-wrvp-9gjr

@jmondi/url-to-png contains a Path Traversal vulnerability

Quick fix

GHSA-vvmv-wrvp-9gjr — @jmondi/url-to-png: upgrade to the fixed version with the command below.

npm install @jmondi/url-to-png@2.1.2

Details

### Summary When trying to add a `BLOCK_LIST` feature when the maintainer noticed they didn't sanitize the `ImageId` in the code, which leads to path traversal vulnerability. Now, this is different from a traditional path traversal issue, because as of NOW you can store the image in any place arbitrarily, and given enough time they might be able to come up with a working exploit BUT for the time being they am reporting this.

### Details

@jmondi/url-to-png does not sanitizing the `ImageID` as in not removing special chars from the params [(extract_query_params.ts#l75)](https://github.com/jasonraimondi/url-to-png/blob/e43098e0af3a380ebc044e7f303a83933b94b434/src/middlewares/extract_query_params.ts#L75)

```js const imageId = dateString + "." + slugify(validData.url) +configToString(params); ```

This when fed to other parts of the code such as ([filesystem.ts#L34](https://github.com/jasonraimondi/url-to-png/blob/8afc00247c1d7e6c7b37356a5f6282b486e596fa/src/lib/storage/filesystem.ts#L34))

```js return path.join(this.storagePath, imageId) + ".png"; ```

Would result in path traversal issue.

### PoC

``` # Configuration for filesystem storage provider (optional) STORAGE_PROVIDER=filesystem IMAGE_STORAGE_PATH=poc ```

Set this in your `.env` file and use this as your payload.

``` http://localhost:3089/?url=http://example.com&width=400&isDarkMode=../../../../../../../../../../../../tmp/hack ```

This will create a `.png` file in the `/tmp` section of the system.

Loom POC: https://www.loom.com/share/bd7b306cdae7445c97e68f0626e743a6

This is valid for pretty much all the arguments (except for numeric values)

A simple fix would be to use the `slugify` for the params as well like so ([#L75](https://github.com/jasonraimondi/url-to-png/blob/e43098e0af3a380ebc044e7f303a83933b94b434/src/middlewares/extract_query_params.ts#L75))

```diff - const imageId = dateString + "." + slugify(validData.url) + configToString(params); + const imageId = dateString + "." + slugify(validData.url) + slugify(configToString(params)); ```

### Impact This would be path traversal vulnerability which allows arbitrary write as of now.

Are you affected?

Enter the version of the package you're using.

Affected packages

npm/@jmondi/url-to-png
Introduced in: 0Fixed in: 2.1.2
Fixnpm install @jmondi/url-to-png@2.1.2

References