cPanel – Modifyacct Input Validation Failure (R911-0122)

Type: Input Validation Failure
Location: Remote
Impact: High
Product: cPanel
Vulnerable Version: All versions prior to the fixed builds below.
Fixed Version:, &
CVE: -
R911: 0122
Date: 2014-02-05
By: Rack911

Product Description:

cPanel is an easy-to-use control panel that gives web hosts and the website owners they serve, the ability to quickly and easily manage their servers and websites. Web Host Manager (WHM) is a part of the cPanel software, often used by resellers and system administrators.

Vulnerability Description:

It is possible for a reseller to evade the actual process of modifying accounts by using a nullbyte (%00) to send commands directly to hooks. There does not appear to be any sanitation of special characters and as such, cPanel has put many plugins that have hooks tied into modifyacct at risk of being compromised.


We have deemed this vulnerability to be rated as HIGH due to the fact that cPanel plugins using various hooks dependent on modifyacct can be compromised.

Vulnerable Version:

This vulnerability was tested against cPanel 11.40.0 #19 and is believed to exist in all versions prior to the fixed builds below.

Fixed Version:

This vulnerability was patched in cPanel, &

Vendor Contact Timeline:

2013-12-25: Vendor contacted via email.
2014-01-08: Vendor confirms vulnerability.
2014-02-03: Vendor issues updates to all builds.
2014-02-05: Rack911 issues security advisory.