CVE-2026-93580 in InPost PL Plugin
Summary
by MITRE • 09/30/2026
The InPost PL WordPress plugin before 1.9.8 does not verify the authenticity of incoming shipment webhook requests, relying only on a non-secret identifier and an IP check that is not enforced, allowing unauthenticated attackers who know a target order's parcel tracking number to forge its shipment status and prematurely mark the order completed.
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Analysis
by VulDB Data Team • 09/30/2026
The vulnerability identified in InPost PL WordPress plugin versions prior to 1.9.8 represents a critical failure in authentication logic for webhook endpoints designed to synchronize shipping data with e-commerce platforms. The core technical flaw lies in the insufficient verification of incoming shipment webhook requests, which are intended to update order statuses based on real-time logistics information from courier services. Instead of employing robust cryptographic signature validation or secure token-based authentication mechanisms as recommended by industry standards such as CWE-287 (Improper Authentication), the plugin relies exclusively on a non-secret identifier and an IP address check that is not strictly enforced. This architectural weakness allows attackers who possess knowledge of a target order's parcel tracking number to bypass security controls entirely, effectively impersonating legitimate courier systems without possessing any valid secrets or credentials.
From an operational perspective, this vulnerability enables unauthenticated remote code execution in the context of business logic rather than system-level compromise. An attacker can forge shipment status updates by sending malicious HTTP requests that mimic those from InPost logistics servers. By manipulating these webhook payloads, the attacker can prematurely mark orders as completed and shipped before actual delivery has occurred or even before payment is fully secured. This leads to significant financial losses for merchants through premature release of funds, inventory discrepancies where stock is deducted without corresponding physical movement, and severe reputational damage due to customer dissatisfaction resulting from false shipping notifications. The lack of enforced IP checking further exacerbates the risk by allowing attacks originating from any network location, removing a potential layer of defense that might have restricted access to known courier infrastructure ranges.
This vulnerability aligns closely with CWE-345 (Insufficient Verification of Data Authenticity) and falls under the MITRE ATT&CK technique T1078 (Valid Accounts), although in this case it exploits the lack of proper authentication for a service account or webhook endpoint rather than stolen user credentials. It also relates to CWE-294 (Authentication Bypass by Capture-replay) if an attacker were to intercept and replay valid-looking requests, though here the primary issue is the ability to forge new requests due to weak validation rules. The absence of HMAC signatures or similar cryptographic proofs means that any entity with network connectivity can inject false data into the application's state machine, violating the principle of trust boundaries between external logistics providers and internal e-commerce systems.
To mitigate this vulnerability, immediate updates to version 1.9.8 or later are required as they address these authentication deficiencies by implementing proper verification mechanisms for webhook requests. In addition to upgrading, administrators should ensure that their web servers enforce strict IP allowlisting if the plugin supports such configuration, although cryptographic validation remains the primary defense. Developers integrating similar plugins in custom environments must adhere to OWASP guidelines for API security, specifically ensuring that all state-changing endpoints require strong authentication and integrity checks using shared secrets or public key infrastructure rather than opaque identifiers alone. Regular auditing of webhook handlers against CWE-287 is essential to prevent future occurrences of this class of business logic exploitation.