CVE-2026-4945 in Otter Blocks Plugin
Summary
by MITRE • 09/07/2026
The Otter Blocks – Gutenberg Blocks, Page Builder for Gutenberg Editor & FSE plugin for WordPress is vulnerable to Insecure Direct Object Reference in all versions up to, and including, 3.1.7 via the 'watch_checkout' function due to missing validation on a user controlled key. This makes it possible for unauthenticated attackers to pay for a lower-cost product while obtaining entitlement for a premium product by manipulating the product_id parameter independently of the price_id parameter in the Stripe checkout URL.
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Analysis
by VulDB Data Team • 09/07/2026
The vulnerability identified within Otter Blocks, specifically affecting versions up through 3.1.7, represents a critical flaw in access control logic known as an Insecure Direct Object Reference or IDOR. This issue is rooted in the implementation of the watch_checkout function, which handles payment processing via Stripe integration for WordPress sites utilizing Gutenberg blocks and Full Site Editing features. The core technical deficiency lies in the absence of server-side validation when processing user-supplied input parameters during checkout transactions. Specifically, the application fails to verify that the product identifier provided by the client corresponds accurately with the pricing tier associated with that specific transaction flow. This lack of binding between the resource identity and its intended cost structure allows for a fundamental bypass of payment integrity controls.
From an operational perspective, this vulnerability enables unauthenticated attackers to exploit the checkout mechanism without needing valid credentials or prior authentication. By manipulating the product_id parameter within the Stripe checkout URL independently from the price_id parameter, an attacker can decouple the item being purchased from its actual cost. For instance, a user might select a premium feature set that requires a high-tier subscription but injects a reference to a basic or free tier product identifier into the request payload. Because the server does not validate this correlation against its internal database of valid price-to-product mappings, it processes the transaction based on the lower-cost entry while granting access rights associated with the higher-value premium entitlement. This results in unauthorized privilege escalation and financial loss for the service provider through underpayment or complete non-payment for high-value digital goods.
The security implications extend beyond immediate revenue loss to include broader integrity concerns regarding user data and system trustworthiness. When an attacker successfully exploits this flaw, they gain access to features or content that should be restricted behind a paywall. This not only compromises the business model of the website owner but also potentially exposes sensitive information if premium tiers contain confidential materials. Furthermore, because the attack vector is unauthenticated, it can be automated and scaled rapidly against any WordPress site running the vulnerable plugin version, posing a significant risk to e-commerce functionality built on this platform. The ease of exploitation means that even attackers with minimal technical expertise can leverage existing exploit tools or simple HTTP request manipulation scripts to achieve unauthorized access.
To mitigate this vulnerability, immediate action is required by administrators and developers using Otter Blocks. The primary remediation step is to upgrade the plugin to version 3.1.8 or later, where the vendor has implemented proper validation checks for the product_id parameter relative to its corresponding price_id. In addition to updating software, organizations should implement defense-in-depth strategies such as server-side verification of all payment-related parameters before processing transactions through third-party gateways like Stripe. It is also advisable to enforce strict input sanitization and ensure that session state or user roles are validated against the requested resource permissions at every step of the checkout process. Regular security audits and penetration testing focused on e-commerce flows can help identify similar logic flaws in other plugins or custom code, ensuring robust protection against IDOR attacks across the entire application stack.