CVE-2011–5251: vBulletin — Unvalidated Redirects

Robert Gilbert
May 25, 2022

Migrating CVE-2011–5251 publication to as part of my Personal CVE-ID Migration Project. This was originally published June 2, 2011. The only major change is moving the CVSS from version 2.0 to 3.1, and updated the title from “Multiple Open Redirects” to “Unvalidated Redirects”.


Multiple Open Redirect vulnerabilities in vBulletin version 4.1.3 and below allow remote attackers to redirect users to arbitrary web sites and conduct phishing attacks via the “url” parameter. By appending ?url= to any number of pages, the user will be redirected to a potentially dangerous site. This is particularly interesting when used on the registration form or the password reset form.


CVSS v3.1 Vector (Medium): AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N/E:F/RL:O/RC:C

Exploit Example



vBulletin’s Advisory:

OWASP Unvalidated Redirects:



Robert Gilbert

Robert Gilbert is an AppSec Engineer at Amazon AWS with over 15 years experience in Offensive Security, & over 20 years experience in Information Systems. OAMO