This article is a part of our Vulnerability Database (back to index)
Cross-site Scripting occurrences in Fortiproxy
An improper neutralization of input during web page generation vulnerability [CWE-79] in FortiOS version 7.0.3 and below, 6.4.8 and below, 6.2.10 and below, 6.0.14 to 6.0.0. and in FortiProxy version 7.0.1 and below, 2.0.7 to 2.0.0 web filter override form may allow an unauthenticated attacker to perform an XSS attack via crafted HTTP GET requests. (2022-05-11, CVE-2021-43081)
Failure to sanitize input in the SSL VPN web portal of FortiOS 5.2.10 through 5.2.15, 5.4.0 through 5.4.13, 5.6.0 through 5.6.14, 6.0.0 through 6.0.12, 6.2.0 through 6.2.7, 6.4.0 through 6.4.4; and FortiProxy 1.2.0 through 1.2.9, 2.0.0 through 2.0.1 may allow a remote unauthenticated attacker to perform a reflected Cross-site Scripting (XSS) attack by sending a request to the error page with malicious GET parameters. (2022-02-24, CVE-2021-26092)
A Cross-site Scripting (XSS) vulnerability in Fortinet FortiOS 6.0.0 to 6.0.4, 5.6.0 to 5.6.7, 5.4.0 to 5.4.12, 5.2 and below and Fortinet FortiProxy 2.0.0, 1.2.8 and below under SSL VPN web portal allows attacker to execute unauthorized malicious script code via the error or message handling parameters. (2019-06-04, CVE-2018-13380)
Why Cross-site Scripting can be dangerous
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>