CVE-2026-93511 in Premium Packages Plugin
Summary
by MITRE • 09/23/2026
The Premium Packages WordPress plugin before 7.2.1 does not verify PayPal's webhook signature before processing payment and subscription notifications, allowing unauthenticated attackers to forge payment confirmations and subscription-cancellation events against any order whose transaction id they know.
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Analysis
by VulDB Data Team • 09/23/2026
The vulnerability identified in the Premium Packages WordPress plugin prior to version 7.2.1 represents a critical failure in cryptographic verification within an e-commerce context. Specifically, the application fails to validate the digital signature of incoming PayPal webhook notifications before processing them. Webhooks are automated messages sent from one application to another when specific events occur, such as a payment being completed or a subscription being cancelled. In secure implementations, these payloads must be cryptographically signed by the sender, in this case PayPal, using a shared secret or public key infrastructure. The absence of signature verification means that any party capable of intercepting network traffic or possessing knowledge of valid transaction identifiers can inject malicious webhook requests directly into the application's processing pipeline without authentication credentials.
From a technical perspective, this flaw constitutes an insecure direct object reference combined with insufficient validation of incoming data. An unauthenticated attacker who knows the transaction ID associated with a specific order on the WordPress site can craft a fake PayPal webhook payload that mimics a legitimate payment confirmation or subscription cancellation event. Because the plugin does not verify that the request actually originated from PayPal's servers and was signed correctly, it blindly trusts the content of these notifications. This allows the attacker to manipulate the state of orders and subscriptions arbitrarily. For instance, an attacker could forge a successful payment notification for an order they did not pay for, thereby granting themselves access to premium features or products without financial compensation. Conversely, they could forge cancellation events to disrupt legitimate subscriber services or trigger refunds fraudulently if such logic is tied directly to webhook status updates.
The operational impact of this vulnerability extends beyond simple financial loss. It undermines the integrity and trustworthiness of the entire e-commerce system built on WordPress using this plugin. Businesses relying on automated payment processing face significant risks including revenue leakage, inventory discrepancies due to false order completions, and potential legal liabilities if subscription terms are violated through forged cancellation events. Furthermore, because the attack requires no authentication, it is easily scalable and can be executed by low-skilled threat actors who simply need access to public transaction IDs or can scrape them from web pages where they might be exposed in URLs or page sources. This lack of integrity control also opens the door for further exploitation if other parts of the application logic depend on these webhook statuses, potentially leading to privilege escalation within the administrative interface if certain actions are triggered by payment status changes.
This vulnerability aligns with CWE-347 Improper Verification of Cryptographic Signature and CWE-285 Improper Authorization, as it involves both a failure in cryptographic validation and an authorization bypass where unauthenticated actors can perform privileged operations like modifying order states. In the context of the MITRE ATT&CK framework, this behavior is consistent with techniques involving Data Manipulation or Impair Defenses, specifically through the forgery of system events to achieve unauthorized objectives without detection by standard authentication mechanisms. The attack vector leverages the trust relationship between the application and its payment gateway provider, exploiting a gap in that chain of trust.
To mitigate this vulnerability, immediate action is required to upgrade the Premium Packages plugin to version 7.2.1 or later where the signature verification logic has been implemented correctly. Until an update can be applied, administrators should consider implementing network-level controls such as firewall rules that restrict incoming webhook traffic exclusively from PayPal's known IP address ranges, although this is a less robust defense than cryptographic validation since IP addresses can change or be spoofed in some contexts. Additionally, enabling two-factor authentication for all administrative accounts and monitoring logs for unusual patterns of order status changes can help detect potential exploitation attempts. It is also advisable to review the implementation of webhook handlers across other plugins to ensure that no similar vulnerabilities exist elsewhere in the WordPress installation, as payment processing systems are high-value targets for attackers seeking financial gain or system compromise.