A critical vulnerability in a widely used WordPress membership plugin recently put sensitive Stripe payment setup data at risk on thousands of websites. The vulnerability gave the chance to attackers who were not authenticated to get Stripe’s client_secret values, which are very important tokens used for customer payment methods – to the attackers without any login or special privileges. The flaw is now fixed, but it highlights the need for plugin security, proper permission checks and proactive patch management for WordPress sites that manage online payments.
The topic of the article is the characteristics of the vulnerability, its importance, the solution applied, and the recommendations for the site owners to ensure the safety of their memberships, subscriptions, and payments. Additionally, it contains well-made FAQs that are designed for Google’s AI Overview, search snippets, and tools like ChatGPT or Perplexity.
What Happened: The Membership Plugin Vulnerability
The vulnerability affected the Membership Plugin – Restrict Content by StellarWP, a plugin commonly used on WordPress sites to manage paid memberships, content gating, and subscription access. The plugin integrates with Stripe to process and save customer payment methods using Stripe’s SetupIntent API.
In all versions up to and including 3.2.16, the plugin’s function that handled Stripe SetupIntents had a missing authentication check. This meant the plugin did not verify whether a request came from a legitimate, authenticated user before responding. As a result, attackers could trigger the function remotely and retrieve Stripe SetupIntent client_secret values — tokens intended only for the customer during secure checkout.
According to security expert Andrea Bocchetti (through Wordfence), the vulnerability – known as CVE-2025-14844 – had a CVSS score of 8.2 (High) which not only indicated its severity but also the fact that no login was required for attackers to exploit it.
Understanding Stripe SetupIntent and Client Secrets
Stripe’s SetupIntent object is part of how merchants securely collect and store payment methods. When a customer adds a card for future charges, Stripe generates a client_secret — a sensitive token used to complete the secure setup on the client side. According to Stripe’s documentation, this client_secret:
- Should only be accessible to the intended customer
- Must not be logged, stored publicly, or exposed to unauthorized parties
- Requires secure transmission over TLS (HTTPS) to prevent eavesdropping
If such client_secret tokens are leaked, attackers might misuse them to create or modify payment setups in unintended ways, potentially enabling unauthorized payment method additions or fraud. While the vulnerability did not directly allow unauthorized charges, it exposed critical data that could enable payment workflow abuse.
How the Flaw Worked
The issue was rooted in a function called:
rcp_stripe_create_setup_intent_for_saved_card
This function handles creating Stripe SetupIntents for saved cards. Because the plugin lacked appropriate authentication and capability checks, and did not validate a user-controlled key, attackers could call the endpoint without being logged in or having any legitimate membership access. This type of weakness is technically described as Missing Authentication and is cataloged under CWE-639 (Authorization Bypass Through User-Controlled Key).
In practice:
- The function responded to external requests.
- No permission verification was enforced.
- Attackers only needed network access to call the endpoint.
- The response included Stripe’s client_secret values tied to payment setups.
Because these values are highly sensitive, their exposure represents a significant confidentiality risk.
Patch and Resolution
The issue has since been patched in version 3.2.17 of the Membership Plugin – Restrict Content. The update adds:
- Nonce checks to verify the request originated from an intentional action
- Permission checks to enforce that only authorized users can trigger payment-related functions
- Improved validation around payment setup workflows
These enhancements prevent unauthenticated attackers from retrieving client_secret data and close the authentication gap that made the exploit possible.
If your site uses this plugin, ensure that it has been updated to 3.2.17 or later immediately. Without the patch, your site could remain susceptible to exploitation.
Real-World Impact
Why This Vulnerability Is Serious
Unlike vulnerabilities that require authenticated access or elevated privileges, this flaw was exploitable without any login, making it significantly easier for attackers to abuse. Because it affected payment integration code, the risk extended to:
- Sensitive payment setup data being retrieved by unauthorized actors
- Potential misuse of client_secret values to manipulate setup flows
- Legal and compliance concerns (e.g., PCI-DSS violations) for sites handling payments
- Loss of customer trust and reputational damage
Because many membership sites rely on Stripe for recurring billing and subscription payments, safeguarding Stripe credentials and API tokens is critical.
Scope of Affected Sites
The figures may differ, but it is certain that this plugin is installed on a lot of WordPress sites dealing with memberships, paid subscriptions, and restricted content—all the way from membership communities to e-learning platforms and premium content websites. A site that uses an unpatched version with vulnerability remained at risk till the update was done.
Best Practices for WordPress Site Security
This incident highlights broader security principles that apply to any WordPress site handling payments or sensitive data. Follow these best practices:
1. Keep Plugins Updated
Always update plugins — especially those handling payments — to the latest versions. Patches like the one for this flaw are released because researchers responsibly disclose issues; delays in updating increase risk.
2. Limit Plugin Usage
Only install plugins that are actively maintained and widely trusted. Reduce unnecessary plugins to minimize attack surface.
3. Use Security Plugins and Firewall
Tools like Wordfence and Sucuri provide active monitoring, firewall protection, vulnerability scanning, and intrusion blocking that can mitigate attempts to exploit weaknesses.
4. Review User Roles and Permissions
Minimize high-privilege accounts and enforce strict role definitions. Even though this specific flaw allowed attacks without login, good access control prevents many other risk scenarios.
5. Secure Stripe Integrations
Follow Stripe’s own security recommendations:
- Never log or expose client_secret values
- Use TLS/HTTPS for all payment pages
- Store sensitive credentials securely and rotate keys periodically
These practices align with PCI compliance and reduce the likelihood of payment data exposure.
FAQs: Membership Plugin Vulnerability and Stripe Data Exposure
Q1: What was the nature of the WordPress plugin flaw?
The vulnerability was a missing authentication check in the Stripe SetupIntent handling code of the Membership Plugin – Restrict Content, allowing unauthenticated attackers to access Stripe client_secret values.
Q2: What is a Stripe client_secret, and why is it sensitive?
The client_secret is a secure token used to complete payment method setup on the client side. It should not be exposed publicly or stored in logs, as misuse can compromise payment workflows.
Q3: Which plugin versions were affected?
All versions up to and including 3.2.16 were vulnerable. The issue is fixed in version 3.2.17 and later.
Q4: Could attackers charge customer cards directly with this flaw?
Not directly. The vulnerability exposed payment setup secrets, not charge APIs. However, misuse of SetupIntent tokens can undermine secure payment setups and enable later unauthorized payment method additions or billing abuse.
Q5: What should site owners do now?
Update the plugin to the latest version, review Stripe integration configurations, monitor for unusual activity, and apply broader WordPress security practices.
Conclusion
The vulnerability of the Membership Plugin – Restrict Content exposes the risks that even minor gaps in authentication and permission checks can lead to the compromising of sensitive payment data. When plugins connect with payment processors such as Stripe, any lapse in security measures can be detrimental to both the site owner and customer.
The good thing about it is that a fix has been rolled out. Still, this incident has brought to light the necessity of:
- Prompt updates
- Secure coding practices
- Ongoing vulnerability monitoring
For any WordPress site handling paid memberships or subscriptions, maintaining robust plugin security is not just best practice — it’s essential for protecting customer trust and financial data.
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