Fatfreecrm Cross-site Scripting

FatFreeCRM version <=0.14.1, >=0.15.0 <=0.15.1, >=0.16.0 <=0.16.3, >=0.17.0 <=0.17.2, ==0.18.0 contains a Cross Site Scripting (XSS) vulnerability in commit 6d60bc8ed010c4eda05d6645c64849f415f68d65 that can result in Javascript execution. This attack appear to be exploitable via Content with Javascript payload will be executed on end user browsers when they visit the page. This vulnerability appears to have been fixed in 0.18.1, 0.17.3, 0.16.4, 0.15.2, 0.14.2. (2018-12-20, CVE-2018-1000842)

Cross site scripting is an attack where a web page executes code that is injected by an adversary. It usually appears, when users input is presented. This attack can be used to impersonate a user, take over control of the session, or even steal API keys.

The attack can be executed e.g. when you application injects the request parameter directly into the HTML code of the page returned to the user:

https://server.com/confirmation?message=Transaction+Complete

what results in:

<span>Confirmation: Transaction Complete</span>

In that case the message can be modified to become a valid Javascript code, e.g.:

https://server.com/confirmation?message=<script>dangerous javascript code here</script>

and it will be executed locally by the user's browser with full access to the user's personal application/browser data:

<span>Confirmation: <script>dangerous javascript code here</script></span>