The Ultimate Flaw in WordPress' 'Ultimate Member' Plugin

Why Design Without Security is Simply Bad Design

Cory Marsh
Cory Marsh
Cory Marsh has over 20 years Internet security experience. He is a lead developer on the BitFire project and regularly releases PHP security and programming videos on BitFire's you tube channel.
ultimate-member, 5 million+ sites hacked
Authentication Bypass Exploit Code Available

WordPress, the open-source giant that powers much of the internet, is often at the forefront when we discuss web vulnerabilities—given its ubiquity, this should come as no surprise. But today, we're not just talking about WordPress. We're focusing on the top-rated plugin known as ",Ultimate Member", a user-profile and membership service that has taken WordPress communities by storm. It promises ease of use, lightweight architecture, and unmatched extendibility. But as often happens when designers prioritize convenience over security, vulnerabilities emerge.

View CVE Report: CVE-2023-3460

View On ultimate-member

View On Trac:

Ultimate Member – User Profile, Registration, Login, Member Directory, Content Restriction & Membership Plugin

"Ultimate Member is the #1 user profile & membership plugin for WordPress. The plugin makes it a breeze for users to sign-up and become members of your website. The plugin allows you to add beautiful user profiles to your site and is perfect for creating advanced online communities and membership sites. Lightweight and highly extendible, Ultimate Member will enable you to create almost any type of site where users can join and become members with absolute ease."

-- ultimate-member
  • Front-end user profiles
  • Front-end user registration
  • Front-end user login

This one is bad...

BitFire's 0-day protection of CVE-2023-3460 vulnerability

Vulnerability Details—A Glaring Oversight

The crux of the issue, listed under its respective CVE, reveals that Ultimate Member versions prior to 2.6.7 do not have adequate measures to restrict the capabilities that can be assigned to new accounts. This makes it possible for an attacker to freely create an account with administrative privileges. To make matters more urgent, this isn't a theoretical problem languishing in a vulnerability database, it's being exploited in real-world scenarios.

Unchecked Power—What Could Go Wrong?

This isn't merely a bug. It's a design flaw—one that gives an inordinate amount of unchecked power to anyone who understands its existence. Allowing arbitrary capabilities to be assigned during user account creation is akin to leaving the keys to your house under the doormat, and then posting a sign that tells everyone where to look.

The Real-World Impact

Let's simplify this: with admin access, an attacker gains the ability to control your site in its entirety. They can alter or delete data, distribute malware, or leverage your site as part of a larger attack on other targets. In essence, this issue doesn't just put your website at risk—it jeopardizes anyone who interacts with it.

Updating is Non-negotiable, But It's Just a Start

The immediate solution here is to update the plugin to version 2.6.7 or later. That said, simply updating won't resolve the underlying issue: a lack of a security-first approach in web development. Don't leave your website security up to plguin developers, install a first class Runtime Application Self Protection firewall on your site and stay protected from this and other nasty security vulnerabilities.

Reflecting on Security Culture

Perhaps the greatest takeaway from this episode is that features and functionalities can never serve as a substitute for robust security controls. That's not a trade-off anyone should be willing to make. Whether you're a plugin developer or a WordPress site owner, remember that every line of code you write or deploy carries with it a responsibility to protect your users.


This vulnerability in Ultimate Member serves as a reminder that when it comes to security, the devil is often in the details—or in this case, the lack thereof. As we move forward in an increasingly connected world, let's not forget that the most beautiful and functional designs are worthless if they expose us to risk. The best design is secure design. Anything less is simply incomplete.

Removed Code
undefined [flaw_file.]
undefined [removed_code.]
Replaced Code
undefined [added_code.]