How a Trusted WordPress Plugin Exposed 100,000+ Sites to Takeover  

CVE-2025-14533 and the Hidden Risk of “Trusted” Plugins 

WordPress powers millions of websites worldwide, accounting for up to 40% of the entire internet. 

As a trusted content management system (CMS) for blogs and websites, security incidents rarely stem from WordPress itself. But this trust can create a dangerous illusion of safety.  

WordPress is not invincible. 

When visibility is fragmented, plugins go unmaintained, and updates are delayed; risk escalates. A single registration request could turn any visitor into an administrator on over 100,000 websites. 

A recently disclosed vulnerability, CVE-2025-14533, highlights this exact problem, affecting websites built on WordPress. 

What Is CVE-2025-14533? 

CVE-2025-14533 is a privilege escalation vulnerability in the Advanced Custom Fields: Extended WordPress plugin. It is rated Critical, with a CVSS score of 9.8. 

When exploited, it allows an unauthenticated attacker to gain administrative-level access to a vulnerable site, without needing valid credentials and without exploiting WordPress core. 

In practical terms, this means an attacker can take full control of the affected website, modify content, install malicious plugins, or create new administrator accounts. 

The risk does not come from WordPress itself, but from how trusted plugins can introduce critical exposure when left unpatched or improperly configured. 

Important Clarification: This Is Not a WordPress-Wide Vulnerability 

It’s important to clarify that CVE-2025-14533 does not affect all WordPress websites. 

This vulnerability only impacts sites that meet a specific set of conditions: 

• The website is built on WordPress 

• The Advanced Custom Fields: Extended plugin is installed 

• The site is running a vulnerable version, i.e. 0.9.2.1. or earlier 

• The plugin’s affected functionality is enabled or exposed 

Only when this exact combination exists does the site become vulnerable.

An attacker doesn’t need to break WordPress to take over a WordPress site; all they need is a site running with this exact combination. With more than 100,000 active installations, it leaves almost all of these websites open to the risk. 

Why CVE-2025-14533 Is a High-Impact Vulnerability 

Unauthenticated privilege escalation is one of the most severe risks a WordPress site can face. When exploited, CVE-2025-14533 allows attackers to gain the highest level of access without valid credentials.  

In a corporate and enterprise environment, it creates a direct path to full administrative control, which can undermine trust and credibility on the whole. 

Once administrative access is achieved, WordPress’s built-in capabilities effectively work against the site’s owner. Administrative privileges grant full control over content, plugins, themes, and user management, turning a single vulnerable plugin into a complete site takeover vector.  

Unlike many WordPress security issues that require phishing, stolen passwords, or authenticated user access, this vulnerability can be exploited directly from the internet. An attacker does not need to compromise WordPress core, bypass authentication controls, or interact with a legitimate user.  

If the vulnerable plugin is installed and the affected functionality is exposed, exploitation is possible. 

The risk is introduced entirely through a trusted third-party plugin, a common blind spot within the WordPress ecosystem. The severity of CVE-2025-14533 is amplified by several factors: 

• No authentication required, lowering the barrier to exploitation 

• No user interaction needed, making automated attacks feasible 

• Administrative privileges granted, enabling total site control 

• High adoption rate, with over 100,000 active installations 

This combination makes CVE-2025-14533 especially attractive to opportunistic attackers scanning the internet for vulnerable WordPress instances.  

How CVE-2025-14533 Plays Out in the Real World 

A web developer relies on the widely trusted Advanced Custom Fields (ACF): Extended plugin. This plugin turns a simple field-entry tool into a full-scale application framework. It allows developers to build complex features, such as user registration and custom admin panels, through a visual interface. This means they can avoid writing hundreds of lines of manual code. 

Phase 1. The Setup: An Innocent Configuration 

The vulnerability originates in the plugin’s insert_user function, which is responsible for converting submitted form data into a user account. 

In this configuration, the custom registration form allows users to specify their own role to differentiate between user types. However, the plugin does not properly validate or restrict the role received from the form. 

The logic becomes, “If the form says this person is an X, then they are an X,” without checking whether the person submitting the form has the authority to grant that role. 

Phase 2. The Discovery: Passive and Opportunistic 

Attackers are not hunting for particular websites. They rely on automated scanning to identify vulnerable WordPress instances, i.e. sites running Advanced Custom Fields: Extended version 0.9.2.1 or earlier.  

Once a match is found, attackers look for publicly accessible forms tied to user creation actions. These endpoints require no authentication and expose exactly the functionality the vulnerability depends on. 

At this point, no interaction with WordPress core is needed. The presence of the vulnerable plugin and an exposed registration workflow is enough to mark the site as exploitable. 

Phase 3. The Exploitation: Trust Without Verification 

The attacker does not submit the form through the normal interface; they intercept the registration request using tools like Burp Suite. 

Rather than supplying an expected role value, they modify the HTTP POST request and set the parameter to role=administrator, then forward the request. 

The vulnerable insert_user function processes the request as-is.  

It detects the administrator role and proceeds without enforcing a whitelist of permitted roles or verifying whether an unauthenticated user is allowed to assign elevated privileges. 

WordPress then executes wp_insert_user() with administrative permissions, and the registration completes successfully. 

Phase 4. The Impact: Full Control 

Within seconds, the attacker gets to use the newly created administrator account. With full administrative privileges, they gain unrestricted control over the site. 

They can install additional plugins, such as a file manager, to access server-side files. They may also inject a small PHP backdoor into the active theme, allowing persistent access even if the malicious account is later removed. 

From there, sensitive data can be accessed and exfiltrated, including customer records containing email addresses, physical addresses, and purchase history. 

What This Means for a Business 

Administrative takeover turns a website into an attacker-controlled distribution point. Businesses risk SEO blacklisting, revenue diversion, and exposure of customer data, all before the breach is even detected internally. 

The Fix: Simple but Critical 

The fix for CVE-2025-14533 is straightforward. Update Advanced Custom Fields (ACF): Extended to version 0.9.2.2 or later. The patched release introduces proper role validation within the insert_user logic, ensuring that roles assigned through forms are restricted to an explicitly allowed set defined by an authenticated administrator. 

If an unexpected or unauthorized role is submitted, the plugin now defaults to a low-privilege role instead of blindly trusting user input. This closes the privilege escalation path entirely, paired with identifying and removing any privilege-escalated accounts as the quickest fix. 

Persistent Access: Why “Deleting the Admin” Isn’t Enough 

Kicking out the malicious admin account feels like a win. Unfortunately, it’s often just the beginning. Once attackers get admin access, they rarely rely on that one account alone. They’ll drop a backdoor in a theme file, install a sketchy plugin, or quietly tweak server-side code so they can walk right back in later. 

This is why cleaning up without visibility is risky.  

If you don’t know all the ways your application can be accessed, you can’t be sure they’re actually closed. 

Why Penetration Testing Is Necessary 

Think of penetration testing as a planned, ethical break‑in. It gives you complete visibility into every path an attacker could use to sneak in. 

Many critical risks originate in application logic that behaves exactly as designed, just not as securely as intended. Features like forms, workflows, and role assignments often work as expected, yet still succumb to vulnerabilities when assumptions are challenged. 

That is the gap penetration testing is designed to expose. 

Testing goes beyond surface-level vulnerabilities and into application logic, user workflows, and trust assumptions. This includes validating whether role assignment can be manipulated, whether unauthenticated endpoints can influence sensitive actions, and whether access controls hold up when requests are intentionally altered. 

The outcome is not just a list of findings, but actionable insight into how an attacker would compromise the application and how to stop it. 

Final Thought 

CVE-2025-14533 is not a WordPress problem. It’s a trust problem. One overlooked assumption in a trusted plugin can turn a functional feature into a full site takeover. If you don’t test your applications the way attackers do, you’re only measuring what’s expected, not what’s exploitable. SQ1 gives you the insight and proof you need to secure your applications effectively. 

Security isn’t proven by patching; it’s proven when exploitation is no longer possible. Looking for WordPress penetration testing? SQ1 helps you validate real-world exploitability. 

FAQ 

1. How to understand the severity of a newly disclosed security vulnerability? 
   Review the CVSS score and known exploits, then assess real exposure, privileges, and data at risk. A quick penetration test confirms whether it’s theoretical or actually exploitable. 

   
   

2. What steps should an organization take when a critical software flaw is announced? 
   Patch immediately, rotate credentials, review logs, and verify no persistence mechanisms were planted. Then, validate fixes through real-world attack simulation to ensure it’s closed. 

   
   

3. Where can I download updates to fix CVE-2025-14533 vulnerabilities? 
   Update the affected plugin from the official WordPress plugin repository or vendor release page. After updating, test the application to confirm the vulnerability can no longer be abused.