Yeswiki Vulnerable to Authenticated Reflected Cross-site Scripting

Summary

Vulnerable Version: Yeswiki < v4.5.4
Vulnerable Endpoint: /?PagePrincipale%2Fdeletepage
Vulnerable Parameter: incomingurl
Payload: "><script>alert(1)</script>

Details

Reflected Cross-Site Scripting (XSS) attacks are a type of injection, in which malicious scripts are injected into otherwise benign and trusted websites. XSS attacks occur when an attacker uses a web application to send malicious code, generally in the form of a browser-side script, to a different end user. Flaws that allow these attacks to succeed are quite widespread and occur anywhere a web application uses input from a user within the output it generates without validating or encoding it.

PoC

NOTE: This vulnerability requires admin access.
1. Visit the endpoint as mentioned below and see that an alert box pops up:

URL with Payload: https://yeswiki.net/?PagePrincipale%2Fdeletepage&incomingurl="><script>alert(1)</script>

Impact

An attacker can use a reflected cross-site scripting attack to steal cookies from an authenticated user by having them click on a malicious link. Stolen cookies allow the attacker to take over the user’s session. This vulnerability may also allow attackers to deface the website or embed malicious content.